TW200532679A - Optical pickup apparatus and diffractive optical element for optical pickup apparatus - Google Patents

Abstract

An optical pickup apparatus, includes: first-third light sources emitting first-third light fluxes respectively; a diffractive optical and; an objective optical system having a light converging element, wherein the diffractive optical element includes a first area whose center is on an optical axis; a second area formed in a ring-shape and arranged outside of the first area; a third area formed in a ring-shape and arranged outside of the second area; and the first-third areas have different optical properties each other for the first-third light fluxes, the third area does not form two light fluxes among the first-third light fluxes passing the third area and the light converging element into a converged spot on the information recording surfaces of corresponding disks.

Description

200532679 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to an optical pick-up device and its winding [prior art] In recent years, in optical pick-up devices, the information used on optical discs and the The wavelength of the light of the information recorded on the optical disc is made shorter and shorter, and, for example, a laser light source (such as an ultraviolet semiconductor laser SHG laser) every 40 5 nm is actually used. Modulation is generated to perform wavelength conversion of body laser. If these UV light sources are used, when an objective lens with the same (numerical aperture) (NA) is used on a DVD (energy disc), it can record 15 to 20 GB of information on a direct-named disc, and when the NA of the objective lens is increased to At 0.85, its memorable information is on a disc with a diameter of 12cm. Hereinafter in this manual, the optical discs and magnetic discs of external light laser light sources are generally referred to as “discs.” At the same time, for disc player and recorder products, the capacity of recording and reproducing information on the disc is not sufficient. All kinds of information are recorded on the DVD and CD (ff), which is sufficient for the high-density optical disc itself to perform recording and reproduction information, and although the DVDs and CDs owned by users are used to facilitate the optical components to be recorded at the source The laser has a wavelength and an external light semi-derivative, an aperture, a digital multifunction of 12 cm, 23 -25 GB, and uses purple high-density light, which is a high-density compact disc in the market today. The ability is different and 200532679 4 (2) Other capabilities to perform recording and reproduction of information will increase the commercial price of optical disc players and recorders. Therefore, it is necessary to make a disc pickup device combined with a high-density disc player and recorder have a record that can properly perform information And the ability to reproduce, while maintaining the same for any high-density optical disc, DVD and CD. Because it is necessary for recording and reproducing information The numerical aperture is established for each optical disc, so it is necessary to provide an aperture adjustment mechanism to obtain the desired numerical aperture to be compatible with the optical pickup device. Regarding this aperture adjustment mechanism, for example, a method of The method of using a diaphragm to mechanically block light rays, a method using wavelengths that are selective for the transmittance of light rays, a method of using a phase control element based on liquid crystal, and a method combining the above. (For example, please refer to The following Patent Document 1) Patent Document 1 discloses an optical pickup device provided separately from an optical element, in which a stereo camera is formed in a region (center region) having a center φ center on an optical axis, and A diffraction grating is formed on the circumference (peripheral area) of the central area and has a refractive objective lens. In this device, a light flux of 63 5 nm for DVD is transmitted, and the diffraction wavelength is 7 8 in the central area. A light flux with a wavelength of 0 nm is used for CD, while a light flux with a wavelength of 63 5 nm is transmitted and a light flux with a wavelength of 7 8 Onm passes through the peripheral area. The diffraction is substantially intercepted. By allowing a luminous flux with a wavelength of 63 5nm to enter the objective lens as a whole, and by passing a luminous flux with a wavelength of 7 80nm so that only the luminous flux is transmitted through the central region to be diffused and diverged into the objective lens (such as (Above), recording and reproduction of information can be performed by -5- 200532679, (3) two kinds of objective lenses including DVD and CD. (Patent Document) International Publication No. 9 8/1 9 3 0 3 The device disclosed in Document 1 has different wavelengths in each of the two types of light fluxes, one of which is diffracted by a stereo photographic optical element, and the other of which is transmitted and converged on an optical disc via an objective lens. p Therefore, in order to make the three types including high-density optical discs, DVDs, and CDs compatible, the wavelength of the luminous flux used to record and reproduce CDs (close to 7 8 Onm) is approximately twice that of high-density for recording and reproduction. The wavelength of the luminous flux of the optical disc (close to 40 Onm), so it is difficult to design a diffraction structure, which can optimize the diffraction action for both the luminous flux of the high-density optical disc and the luminous flux of the CD, causing problems. Since the above-mentioned problems must be solved, it is difficult to use the technology in the above-mentioned patent document because it is to achieve compatibility for the three types of optical discs. φ Further, although a spectroscopic filter is used, it is difficult to form a thin film that can appropriately adjust the holes for each of three types of light fluxes of different wavelengths, and its cost increases, causing problems. [Summary of the Invention] In consideration of the above problems, an object of the present invention is to provide an optical pickup device having a hole that can be appropriately adjusted for three types of discs including a high-density optical disc using a UV laser light source, a DVD, and a CD. Optical Element-6-200532679 (4) In order to solve the above problems, the optical pickup device of the present invention has a diffractive optical element disposed on a general optical path of first to third light fluxes, and an optical surface of the diffractive optical element The system is divided into first to third regions, and the second and third regions are respectively provided with a first diffraction structure and a second diffraction structure. Each of the first to third luminous fluxes passing through the first area forms a convergence point on the information recording surface of each of the above-mentioned optical discs. The first light source and the second light source passing through the second area also individually form a convergence point. g The third luminous flux in the second region does not form a convergence point, so a convergence point is formed to pass through either the first luminous flux and the second luminous flux in the third region, while the other luminous fluxes and the third luminous flux that pass through the third region do not form A convergence point. In this specification, optical discs that use ultraviolet semiconductor lasers and ultraviolet SHG lasers for recording and reproducing information are generally referred to as "high-density optical discs." They also include a protective layer with a thickness of about 0.6 mm and a A φ-standard optical disc having an objective lens system with NA of 0.65 to 0.67 for recording and reproduction of information (for example, HD DVD 'hereinafter referred to as HD), and an objective lens system having a protective layer thickness of about 0.1 mm and an NA of 0.85 A standard optical disc for recording and reproducing information (such as a Blu-ray disc, hereinafter referred to as BD). Further, in addition to the optical disc having such a protective layer on the information recording surface thereof, it also includes an optical disc whose information record indicates a protective layer having a thickness of several tens of micrometers and an optical disc having a protective layer or a protective film having a thickness of zero. In this specification, the package density optical disc also includes a magnetic optical disc using ultraviolet semiconductor laser and ultraviolet SHG laser as light sources to record and reproduce information. v 200532679 (5) In this manual, DVD is the general name of the DVD series, such as DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD + R and DVD + RW, and CD is the general name of CD series CDs, such as CD-ROM, CD-Audio, CD-Video, CD-R and CD-RW. Further, in the present specification, the "target optical system" refers to an optical system that is disposed at a position of a disc in a surface pickup position in an optical pickup device | 'and includes at least one light converging element having The function of light flux convergence and having a different wavelength on each information recording surface of each optical disc with a different recording density. The target optical system may be composed of only a light converging element. Further, when there is an optical element for tracking and focusing by combining the above-mentioned optical convergence element and a transmitter, the optical element including the optical element and the light conversion element is the target optical system. [Embodiment] An embodiment of the present invention will be described below with reference to the drawings. The optical pickup device according to the present invention includes a first light source emitting a first light flux with a wavelength of λ 1, a second light source emitting a second light flux with a wavelength λ 2 (λ 2 > λΐ), and a light source having a wavelength of λ 3 Third light source with a third light flux (λ3 > λ2) and a target optical having a light converging element for converging the first light flux, the second light flux, and the third light flux on the information recording surface of the first optical disc having a protective substrate thickness ti The system has a data recording surface for protecting a second optical disc with a substrate thickness t2 (t2-tl) 200532679 (6) and an information recording surface for a third optical disc with a protective substrate thickness t3 (t3 > t2). A diffractive optical element is disposed in the optical pickup device, the diffractive optical element is disposed on a common optical path of the first to third light fluxes, and the optical surface of the diffractive optical element includes a first region which is concentric In the form of a circle with its center at the optical axis and including the optical axis, a second region is a concentric circle with its center at the optical axis and is formed outside the first region and has a first diffraction structure, And a third region is a p-concentric circular type having a center on the optical axis and formed on the outer side of the first region and has a second diffraction structure. Thereafter, the first to third light fluxes passing through the first region and the light converging element form convergence points on the information recording surface of the optical disc, and the first to second light fluxes passing through the second region and the light converging element are respectively on the optical disc. The information recording surface forms a convergence point, the third light flux passing through the second region and the light convergence element forms a convergence point on the information recording surface of the optical disc and the light convergence element does not form a convergence point on the information recording surface of the third optical disc, One of the first luminous flux and the second luminous flux passing through the third region and the light converging φ element forms a convergence point on the information recording surface of the optical disc, and the other luminous flux and the third luminous flux pass through the third region and the light converging element. No convergence point is formed on the information recording surface of the optical disc. Preferably, the diffractive structure is formed by an optical element. Further, preferably, the second and third regions are formed on an optical surface of the optical element, or the second region is formed on an optical surface of the optical element, and the third region is formed on the opposite side of the optical element. Optical surface. Since the second and third regions are formed on the above-mentioned optical element, compared with the formation of the second and third regions on several optical elements, the time of assembly and alignment can be saved and energy. Further, it is preferable that the first diffractive structure has a third luminous flux diffracting to pass through the second region, and the second diffractive structure provides ~ a diffractive action to another first luminous flux passing through the third region. With the second luminous flux. Therefore, it can adjust the aperture by the diffraction action. The use of diffraction to create a flare is somewhat free of the shape of the flare and reduces the noise caused by the flare light reflection on the optical information recording surface. It can form a first diffraction structure in the second region, provide a second diffraction structure in the third region, and give a diffraction action to the third light flux passing through the first and second diffraction structures. As a result, a light spot member in the form of a light spot is not caused on the information recording surface of the third optical disc as described above, so that the optical disc pickup device has an aperture adjustment regarding the third light flux. Further, 'it enables the optical pickup device to have an aperture adjustment function with respect to the second light flux by giving a diffraction action to the second light flux passing through the second diffraction structure' so as not to cause an information recording surface on the second optical disc. Spots that form spots. Therefore, in an optical pickup device having compatibility with three types of optical discs, it does not need to use a beam splitter or a liquid crystal phase control element, for example, and it can reduce the manufacturing cost of the optical pickup device. Preferably, the first diffraction structure is constituted by an annular region in the form of a concentric circle, and each has a step structure (step structure) formed by a step portion -10- 200532679 (8) and has a preset Non-continuous part of the quantity 'and it is set to have substantially no phase difference for the first and second luminous fluxes of the two regions, and the second structure is formed by a concentric circular ring-shaped region, each with its center system, It has a step structure formed by step parts (steps and non-continuous parts of a preset amount ') and is established to have no phase difference for other luminous fluxes substantially in the three regions. Under this structure, it can provide for any Luminous flux of wavelength

I preferably satisfies the following, where η 1 represents the diffraction coefficient of the diffracted light of the wavelength λ 1, d 1 represents the depth of the portion in the optical axis direction in the first diffraction structure, and M 1 (integer) represents the number of discontinuous portions , Number) represents the step portion in the direction of the optical axis in the second diffractive structure, where d = into l / (nl-1). 4.8 X d ^ dl ^ 5.2 xd? 2 ^ M1 ^ 4 1.9 xd $ d2S2.1 xd, 4SM2S6 φ Satisfying the above expressions will realize the difference of the optical paths for the first and second luminous flux with most integers, so it will not cause The phase is not diffracted, and the phase difference is only for the third luminous flux, and has to be wound (in the first diffractive structure). On the other hand, the optical path given a substantial majority of the first and third light fluxes in the second diffraction structure does not perform diffraction because there is no phase difference, so the diffraction action is performed only for the second light phase difference. At the same time, when the first diffraction structure and the second diffraction are formed on different optical surfaces of the diffractive optics, this effect is particularly remarkable. Pass the first diffraction knot in the shape of the optical axis) Pass the step d2 of the first kinematical element (whole depth to get the real difference, and in the radiating action, give the difference, the flux has the element's radiating structure-11-200532679 (9) most Fortunately, the optical pickup device satisfies the following expression: 4.8 X d ^ dl ^ 5.2 xd, 2 ^ M1 ^ 4 0.9xdgd2 $ l.lxd, M2 = 2 satisfying the above expression will make the first and second light fluxes The optical path difference of most integers does not cause a phase difference without diffraction. Instead, a phase difference is performed only for the third luminous flux, and a diffraction action is performed (in the first diffraction structure). In the second diffraction The structure, on the other side, is the optical path difference that gives a substantial majority of the integer for the first luminous flux, and does not perform diffraction because it does not cause a phase difference. Therefore, it is performed for the second and third luminous fluxes. Diffraction action. At the same time, when the first diffraction structure and the second diffraction structure are individually formed on the same optical surface of the diffractive optical element, the effect is particularly remarkable. Another aspect of the present invention is to include an emission wavelength. A first light source with a first luminous flux of λΐ, a second light source (λ2 > λΐ) emitting a second luminous flux with a wavelength of λ2, a third light φ source (λ3 > λ2) emitting a third luminous flux with a wavelength of λ3 ), And an information recording surface for a first optical disc with a protective substrate thickness t1, an information recording surface for a second optical disc with a protective substrate thickness t2 (t2-t1), and a protective substrate thickness t3 (t3 > t2) An objective optical system of a first light flux, a second light flux, and a light converging element on which the third light flux converges on the information recording surface of the third optical disc. A diffractive optical element is provided in the optical pickup device, and the diffractive optical element The element is constructed on a common optical path of the first to third luminous fluxes, and the optical surface of the diffractive optical element includes a concentric circle with a center on an optical axis and including the optical axis, and has a first winding -12- 200532679 (10) a radiating structure, a first region, having a center on the optical axis in the form of a concentric circle, formed outside the first region, and having a second diffractive structure A second region 'and a center circle form have a third region whose center is on the optical axis and is formed on the outside of the first region. Then, the first through third regions passing through the first region and the light converging element are formed. The light flux individually forms a convergent light spot on the information recording surface of the preset optical disc. The first and second light fluxes passing through the second region and the light converging element individually form a convergent light spot on the information recording surface of the preset optical disc. And the third luminous flux passing through the second region and the light converging element does not form a convergent light spot on the information recording surface of the third luminous flux, and either the first luminous flux and the second luminous flux passing through the third region and the light converging element Convergent light spots are formed on the information recording surface of the preset optical disc, and other light fluxes and third light fluxes passing through the third region and the light converging element do not form convergent light spots on the information recording surface of the preset optical disc. In the above structure, it can make the optical pickup device have an aperture adjustment function with respect to the third Φ light flux, because the first diffraction structure is formed in the first area, the second diffraction structure is located in the second area, and the first The third luminous flux of the first and second diffractive structures is a light spot portion, which does not cause the formation of light spots on the information recording surface of the third optical disc. Further, it enables the optical pickup device to have an aperture adjustment function with respect to the second light flux, because the second light flux passing through the third area is a light spot portion, which does not cause a light spot on the information recording surface of the second optical disc to form. Therefore, in the optical pickup device compatible with the three types of optical discs, its -13-200532679 (11) does not require the use of a beam splitter or a liquid crystal phase control element as the aperture mechanism, and it can reduce the manufacturing cost of the optical pickup device . Preferably, the diffractive structure is formed by an optical element. Further, preferably, the second and third regions are formed on an optical surface of the optical element, or the second region is formed on an optical surface of the optical element, and the third region is formed on the opposite side of the optical element. Formed on an optical surface. Because the second and third regions are formed on one of the above-mentioned optical elements, they can save time and the force of assembly and alignment, as well as the space of the optical elements (compared to the second and third regions formed on several optical elements). Third area). Further, preferably, the first diffractive structure has a second luminous flux that diffracts through the first region, and the second diffractive structure provides a second luminous flux and a third luminous flux that diffractive through the second region. As described above, it can correct the spherical aberration of the second luminous flux by providing the first diffraction structure, and increase the degree of freedom for the magnification relationship of compatible optical pickup devices (for example, when the first wavelength and the second wavelength are infinite) Magnification relationship when large Φ light flux enters the objective optical element). The first diffractive structure can be structured by forming an annular region of concentric circles, each having a center on the optical axis, a stepped structure (stepped structure) formed by a stepped portion, and a preset Non-continuous part of the quantity, and it is set to have substantially no phase difference for the first and third luminous fluxes passing through the second area, and the second diffraction structure is formed by a concentric circular ring-shaped area, each of which The center is on the optical axis, which has a step structure (step shape) formed by a step portion and a non-continuous portion of a preset amount, and is established to have no other luminous flux substantially passing through the second region. Phase difference -14- 200532679 (12) This structure can provide a diffractive action with an arbitrary luminous flux. It is preferable to satisfy the following, where n1 represents the diffraction coefficient of a diffractive member with a wavelength of λ1, d1 represents the depth in the first-order diffraction structure at the square-order portion of the optical axis, and M1 (integer) represents the non-continuous portion. (Integer number) represents the step size in the direction of the optical axis in the second diffraction structure, where d = λ 1 / (nl — 1). 1.9 xd ^ dl ^ 2.1 xd? 4 ^ M1 ^ 6 4.8 xd $ d2S5.2 xd, 2 $ M2 $ 4 satisfying the above expressions will realize the difference in optical path between the first and second luminous flux quality of most integers, so it will not As a result, no diffraction occurs in the phase, and the phase difference is only for the third luminous flux, and has to be wound (in the first diffraction structure). On the other hand, the optical path given a substantial majority of the first and third light fluxes in the second diffraction structure does not perform diffraction because there is no phase difference, so the diffraction action is performed only for the second light phase difference. At the same time, when the first diffraction structure and the second diffraction are formed on different optical surfaces of the diffractive optics, this effect is particularly remarkable. Preferably, the optical pickup device satisfies the following expression. 1.9 X d ^ dl ^ 2.1 X d? 4 ^ M1 ^ 6 〇9 xd ^ d2S 1.1 χ d, 2 $ M2S5 satisfying the above expression will make the optical path difference for the first and second luminous flux substantially a whole number of integers, Therefore, it does not cause the step of the optical wavelength of the phase wavelength. In the action of d2 (deep depth), the difference is given, and the difference is given. The flux has the radiation structure of the element and the difference is given. -15- 200532679 (13) No diffraction Generated, while only giving a phase difference to the third luminous flux, and performing a diffractive action (in the first diffractive structure). In the second diffractive structure, on the other hand, a substantial majority of the integer is given to the first luminous flux. The optical path is different, and diffraction is not performed because it does not cause a phase difference. Therefore, only the second and third light fluxes are given a phase difference to perform a diffraction action. At the same time, when the first diffraction structure and the second diffraction structure are separate The effect is particularly pronounced when formed on the same optical surface of the diffractive optical element. | The second area of the optical pickup device is a concentric circle shape, each centered on the optical axis, and is divided into at least two areas Which includes The 2A region close to the optical axis and the 2B region farther from the optical axis, and the second diffraction structure formed on the 2A region is different from the shape of the second diffraction structure formed on the 2B region. By dividing this area, it is possible to obtain the freedom of the shape of the light spot and reduce the noise caused by the reflection of the light spot on the optical information recording surface. Φ The best wavelength λ 1 -wavelength λ 3 is satisfied in the optical pickup device. The following: 3 70nm ^ λ 1 ^ 440nm 62 Onm ^ λ 2 £ 690nm 750nmg Λ 3 $ 820nm The diffractive optical element in the optical pickup device is preferably a lens of a miniature objective lens optical system. At the same time, it is preferable that the optical pickup The device satisfies the following equation, fl X ΝΑ > f2 χ NA2 > f3 x NA3 -16- 200532679 (14) and preferably performs diffraction for the second luminous flux passing through the third region. In the following expression, each f 1, f2, and f3 represent the focal length of each wave objective optical element, and each NA, NA2, and the number of apertures necessary to record or reproduce each disc. The above diffraction structure can be borrowed in the third area By winding The two light flux speckles are obtained by the action. The diffraction action provides a degree of freedom to design the p pickup device, and can reduce noise caused by light reflection on the optical information recording surface. It is preferable that the optical pickup device satisfy the following expression 0.75 ^ NA1 ^ 0.90 0.60 ^ NA2 ^ 0.70 0.43 ^ NA3 ^ 0.55 Therefore, by the diffraction action, a second light spot can be obtained in the third region. This diffraction action provides a degree of φ in the design of the optical pickup device, and can reduce noise caused by light spots on the optical information recording surface. Preferably, the optical pickup device satisfies the following expression. 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 ^ NA3 ^ 0.55 Therefore, it can obtain a second amount of light spots in the third region by the diffraction action. This diffraction action provides freedom in designing the optical pickup device, and can reduce the reflection on the freely reflected light flux from NA3 to the optical light flux due to the long light spot motion on the optical information recording surface. 17- 200532679 (15 ). Meanwhile, it is preferable that the optical pickup device satisfies the following expression. ΐ2 X ΝΑ2 > fl X ΝΑΙ > f3 χ NA3 and it is preferable to perform a diffraction action on the second luminous flux passing through the third region. In the above expressions, each of Π, f2, and f3 represents the focal length of the objective optical element of each wavelength, and each of NAI, NA2, and | NA3 represents the number of apertures necessary to record or reproduce each optical disc. The above-mentioned diffraction structure can obtain the first luminous flux light spot through the diffraction action in the third region. The diffraction action provides a degree of freedom to design the optical pickup device, and can reduce noise caused by reflection of light spots on the optical information recording surface. Preferably, the optical pickup device satisfies the following expression. 0.64 ^ ΝΑ1 ^ 0.65 0.64 ^ ΝΑ2 ^ 0.70 • 0.43 ^ ΝΑ3 ^ 0.55 Therefore, by the diffraction action, the first light flux spot can be obtained in the third region. This diffraction action provides a degree of freedom in the design of the optical pickup device 'and can reduce noise caused by speckle reflection on the optical information recording surface. Another aspect of the present invention includes a first light source having a first luminous flux having a wavelength of 11; a second light source having a second luminous flux having a wavelength of λ2 (λ2 >Λ1); and a third light flux having a third luminous flux having a wavelength of λ3. A third light source (λ 3 > λ 2), and an information recording surface for the first optical disc with a protective substrate thickness of 18-200532679 (16) tl, and a protective substrate thickness t2 (t2 -tl) Objective optical system of the first optical flux, the second optical flux, and the third optical flux on the information recording surface of the second optical disc and the third optical disc with a protective substrate thickness t3 (t3> t2) . A diffractive optical element is disposed in the optical pickup device. The diffractive optical element is constructed on a common optical path of the first to third luminous fluxes. The optical surface of the diffractive optical element includes a concentric circular shape with a g A center having an optical axis and including the optical axis and a first region having a first diffractive structure, and having a center in the form of a concentric circle on the optical axis and formed outside the first region and having A second region of a first diffractive structure, and a third region of a concentric circle having a center on the optical axis and formed outside the first region and having a second diffractive structure. Thereafter, the first to third luminous fluxes passing through the first region and the light converging element individually form convergent light spots on the information recording surface of the preset optical disc, and the first and second luminous fluxes passing through the second region and the light converging element. Individually, a convergent light spot is formed on the information recording surface of a preset φ disc, and the third light flux passing through the second region and the light converging element does not form a convergent light spot on the information recording surface of the third light flux, and passes the first Either the first luminous flux and the second luminous flux of the three regions and the light converging element form a convergent light spot on the information recording surface of the preset optical disc, and the other luminous flux and the third luminous flux passing through the third region and the light converging element No convergent light spots are formed on the information recording surface of the preset disc. In the above structure, it can make the optical pickup device have an aperture adjustment function with respect to the third light flux, because the first diffraction structure is formed in the second-19-200532679 (17) region, and the second diffraction structure is located in the second Three areas, and the third luminous flux passing through the first and second diffractive structures is a light spot portion, which does not cause the formation of light spots on the information recording surface of the third optical disc. Further, it can make the optical pickup device have an aperture adjustment function with respect to the second light flux, because the second light flux passing through the second diffraction structure is a light spot portion, which does not cause light spot formation on the information recording surface of the second optical disc . Therefore, in the optical pickup device compatible with the three types of optical discs, it does not need to use a beam splitter or a liquid crystal phase control element as the aperture mechanism, and it can reduce the manufacturing cost of the optical pickup device. Preferably, the diffractive structure is formed by an optical element. Further, preferably, the second and third regions are formed on an optical surface of the optical element, or the second region is formed on an optical surface of the optical element, and the third region is formed on the opposite side of the optical element. Formed on an optical surface. Because the second and third regions are formed on one of the optical elements described above, Φ can save time and the force of assembly and alignment, as well as the space of the optical elements (compared to the second and third regions formed on several optical elements). Third area). Further, preferably, the first diffractive structure has a third luminous flux that diffracts through the second region, and the second diffractive structure provides other luminous flux that diffracts through the third region. Therefore, it can realize the aperture adjustment by performing the diffraction action. Making a spot by using a diffraction action 'can give the spot a degree of freedom in the shape of the light and reduce the noise on the optical information recording surface by reflecting the light of the spot. -20- 200532679 (18) It can be structured by forming concentric circles, each having its center on the optical axis, and having a ladder structure (step structure) shaped by step parts And a non-continuous portion with a predetermined amount 'setting is substantially different for the first and second luminous fluxes passing through the second area, and the second diffractive structure is formed by a concentric circular ring-shaped area, and each of its centers is On the optical axis, there is a ladder structure (step shape) formed by a step portion and a non-continuous portion of a preset amount ', and g is no for the other luminous flux substantially passing through the third region. This structure provides a diffractive action with an arbitrary light flux. It is preferable to satisfy the following, where η 1 represents the diffraction coefficient of a diffractive member with a wavelength of λ 1, d 1 represents the depth of the square-order portion of the optical axis in the first diffraction structure, and M 1 (integer) represents a discontinuous portion The number of integers) represents the spring degree of the step portion in the direction of the optical axis in the second diffraction structure, where d = Al / (nl−l). 4.8 X d ^ dl ^ 5.2 X d, 2 ^ M1 ^ 4 1.9 xd ^ d2 ^ 2.1 xd? M2 satisfies the above expressions to realize the difference in optical path between the first and second luminous flux with most integers, so it will not cause The phase is not diffracted, and the phase difference is only for the third luminous flux, and has to be wound (in the first diffractive structure). On the other hand, the optical path that gives a substantial majority of the first and third luminous fluxes in the second diffraction structure does not perform diffraction because there is no phase difference, so only for the order of the second light diffraction structure and its No phase is formed. The order of success is determined by the step of establishing the optical element direction of the phase difference wavelength. D2 (deep depth to obtain a real difference, and in the shooting action, for the difference, the flux is -21-200532679 (19) Phase difference is performed around At the same time, this effect is particularly remarkable when the first diffraction structure and the second diffraction structure are formed on the individual different optical surfaces of the diffractive optical element. Preferably, the optical pickup device satisfies the following expression. 4.8 X d ^ dl ^ 5.2 xd? 2 ^ M1 ^ 4 〇9xd ^ d2 ^ 1.1xd? M2 = 2 Satisfying the above expression will make p for the first and second luminous fluxes give p a substantial majority of the integer optical path difference, so Does not cause phase difference without diffraction, and only gives phase difference for the third luminous flux, and performs diffraction action (in the first diffraction structure). In the second diffraction structure, on the other hand, it is for the first Luminous flux The difference between the optical path and the substantial majority of integers' does not perform diffraction because it does not cause a phase difference. Therefore, only the first and second light fluxes are given a phase difference to perform a diffraction action. At the same time, when the first diffraction structure and the first The two diffractive structures are individually formed on the same optical surface of the diffractive optical element to make the effect particularly remarkable. 另一 Another diffractive optical element of the optical pickup device of the present invention is a diffractive optical element of an optical pickup device, including A first light source emitting a first light flux with a wavelength of λ 1, a second light source emitting a second light flux with a wavelength of λ 2 (λ 2 > λΐ), a third light source emitting a third light flux with a wavelength of λ 3 (λ 3 > λ 2), and an information recording surface for a first optical disc with a protective substrate thickness t1, an information recording surface for a second optical disc with a protective substrate thickness t2 (t2-tl), and a protective substrate thickness t3 ( t3 > t2) Objective optics on which the first light flux, the second light flux, and the third light flux on the information recording surface of the third optical disc converge-22- 200532679 (20) The diffractive optical element is disposed in an optical system of an optical pickup device, the diffractive optical element is constructed on a common optical path of the first to third light fluxes, and the optical surface of the diffractive optical element includes an A concentric circular form having a center on an optical axis and including the optical axis, a first region having a first diffraction structure, and a concentric circle having a center on the optical axis and formed on the first region A second region on the outer side and having a second diffractive structure, and a concentric circular form having a center on the optical axis and a third region formed on the outer side of the first region. Thereafter, the first to third luminous fluxes passing through the first region and the light converging element individually form convergent light spots on the information recording surface of the preset optical disc, and the first and second luminous fluxes passing through the second region and the light converging element. Individually, a convergent light spot is formed on the information recording surface of the preset optical disc, and the third luminous flux passing through the second region and the light converging element does not form a convergent light spot on the information recording surface of the third luminous flux. Any one of the first luminous flux and the second luminous flux of the region and the light converging element forms a convergent light spot on the information recording surface φ of the preset optical disc, and the other luminous flux and the third luminous flux passing through the third region and the light converging element No convergent light spots are formed on the information recording surface of the preset disc. In the above structure, it can make the optical pickup device have an aperture adjustment function with respect to the third light flux, because the first diffraction structure is formed in the first area, the second diffraction structure is located in the second area, and the first The third luminous flux with the second diffraction structure is a light spot portion, which does not cause the formation of light spots on the information recording surface of the third optical disc. Further, it can make the optical pickup device have an aperture adjustment function regarding the second light flux-23- 200532679 (21), because the second light flux passing through the third area is a light spot portion, which will not cause information recording of the second optical disc Spots on the surface are formed. Therefore, in the optical pickup device compatible with the three types of optical discs, it does not need to use a beam splitter or a liquid crystal phase control element as the aperture mechanism, and it can reduce the manufacturing cost of the optical pickup device. Preferably, the diffractive structure is formed by an optical element. Further, it is preferable that the second and third regions are formed on an optical surface of the optical element, or the second region is formed on an optical surface of the optical element, and the third region is formed on the optical element. Opposite optical surfaces are formed. Because the second and third regions are formed on the above-mentioned one optical element, it can save time and the force of assembly and alignment, as well as the space of the optical element (compared to the second and first regions formed on several optical elements). Three zones). Further, preferably, the first diffractive structure has a second luminous flux diffractive to pass through the first region, and the second diffractive structure provides a second luminous flux and a third luminous flux to diffract to pass φ through the second region. As described above, it can correct the spherical aberration of the second luminous flux by providing the first diffraction structure, and increase the degree of freedom for the magnification relationship of compatible optical pickup devices (for example, when the first wavelength and the second wavelength are infinite) Magnification relationship when a large luminous flux enters the objective optical element). The first diffractive structure can be structured by forming an annular region of concentric circles, each having a center on the optical axis, a stepped structure (stepped structure) formed by a stepped portion, and a preset Non-continuous part of the amount, and it is set to be substantially phase-free for the first and third luminous fluxes passing through the second region -24- 200532679 (22) difference, and the second diffraction structure is formed by a concentric circular ring Each of its centers is on the optical axis, which has a ladder structure (step shape) formed by a step portion and a non-continuous portion of a preset amount, and is for other luminous flux substantially passing through the second area is Without it, it can provide a diffractive action with any light flux by this structure. p preferably satisfies the following, where η 1 represents the diffraction coefficient of a diffractive member with a wavelength of λ 1, d 1 represents the depth in the first-order diffraction structure at the square order portion of the optical axis, and M 1 (integer) represents a discontinuity The number of parts is an integer) represents the step in the direction of the optical axis in the second diffraction structure, where d = Al / (nl — 1). 1.9 X dl ^ 2.1 X d5 Ml ^ 6 4.8 xd ^ d2 ^ 5.2 xd, 4 ^ M2 ^ 6 Satisfying the above expressions will realize the difference in optical paths for the first and second luminous flux φ prime multiple integers, so it will not cause The phase is not diffracted, and the phase difference is only for the third luminous flux, and has to be wound (in the first diffractive structure). On the other hand, the optical path given a substantial majority of the first and third light fluxes in the second diffraction structure does not perform diffraction because there is no phase difference, so the diffraction action is performed only for the second light phase difference. At the same time, when the first diffraction structure and the second diffraction are formed on different optical surfaces of the diffractive optics, this effect is particularly remarkable. Preferably, the optical pickup device satisfies the following expression. Formation, the order of formation is through the step of establishing the optical element direction of the phase difference wavelength, d2 (deep depth to get the real difference, and in the shooting action, giving the difference, the flux has the element's shooting structure-25- 200532679 (23) 1.9 xd $ dl € 2.1 xd, 4SM1S6 0.9xd ^ d2 ^ 1.1xd92 ^ M2 ^ 5 Satisfying the above expression will make the optical path difference of a substantial majority of integers for the first and second luminous fluxes, so there is no phase difference without winding The diffraction is generated, and only the third luminous flux is given a phase difference, and a diffraction action is performed (in the first diffraction structure). In the second diffraction structure, on the other hand, the first luminous flux is given a substantial majority integer The optical path difference is different, and the diffraction is not performed because it does not cause a phase difference. Therefore, only the second and third luminous fluxes are given a phase difference to perform the diffraction action. At the same time, when the first diffraction structure and the second diffraction The diffractive structure formed on the same optical surface of the diffractive optical element will make the effect particularly remarkable. The second area of the optical pickup device is a concentric circle shape, each centered on the optical axis, and is divided into There are two regions, including the 2A region closer to the optical axis and the 2B region farther from the optical axis, and the second diffraction structure formed on the 2A region and the second diffraction φ formed on the 2B region The shape of the radiation structure is different. By dividing the area as described above, it can obtain the freedom of the shape of the light spot and reduce the noise caused by the reflection of the light spot on the optical information recording surface. Its best wavelength λ 1 -wavelength λ 3 satisfies the following in an optical pickup device: 3 70nm ^ λ 1 440nm 6 2 0 nm ^ 690nm 7 5 0nm ^ λ 3 ^ 8 2 0nm

A 26- 200532679 (24) Preferably, the optical pickup device satisfies the following expression. 0.75 ^ NA1 ^ 0.90 0.60 ^ NA2 ^ 0.70 0.43 ^ NA3 ^ 0.55 It is preferable to perform a diffraction action for the second luminous flux passing through the third region. The diffraction action provides a degree of freedom in designing the optical pickup device and can reduce noise caused by the reflection of the spot light on the optical information recording surface. Preferably, the optical pickup device satisfies the following expression. 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 ^ NA3 ^ 0.55 It is best to perform a diffraction action for the second luminous flux passing through the third region. The diffraction action provides a degree of freedom in designing the optical pickup device and can reduce noise caused by the reflection of the spot light on the optical information recording surface. Preferably, the optical pickup device satisfies the following expression. 0.64 ^ NA1 ^ 0.65 0.64 ^ NA2 ^ 0.70 0.43 ^ NA3 ^ 0.55 It is best to perform a diffraction action for the second luminous flux passing through the third region. The diffraction action provides a degree of freedom in designing the optical pickup device and can reduce noise caused by the reflection of the spot light on the optical information recording surface. Another diffractive optical element of the optical pickup device according to the present invention is an optical pickup device for recording and / or reproducing information on an information recording surface of an optical disc having a protective substrate with a predetermined thickness, including: a first -27- 200532679 (25) a light source emitting a first light flux having a wavelength λ 1 for recording and / or reproducing information on an optical recording surface of a first optical disc having a protective substrate with a thickness of 11; a second light source, Emitting a second light flux having a wavelength λ2 (λ2 > λΐ) to record and / or reproduce information on an optical recording surface of a second optical disc having a protective substrate having a thickness t2 (t2-tl); a second light source, emitting a wavelength The third luminous flux of λ2 (λ3 > A2) records and / or reproduces information on the optical recording surface of the third optical disc p with a protective substrate having a thickness t3 (t3 >t2); a diffractive optical element to emit the first To a third light flux; and an objective optical system having a light converging element for converging the first to third light fluxes passing through the diffractive optical element to the first to third optical discs individually. The diffractive optical element includes a first region in which the center is received on the optical axis; a second region formed in a ring shape and constructed along the perpendicular to the optical axis outside the first region; a third region to The ring shape is formed outside the second area along the direction perpendicular to the optical axis; and the _th area, the second area, and the third area have optical characteristics different from each other φ for the first to third light fluxes. The three areas do not form the second light flux that passes through the third area and the first to third light fluxes of the light converging element are convergent light spots on the information recording surface of the corresponding optical disc. Preferably, the optical pickup device satisfies the following expression. 370nm ^ λ 1 ^ 44Onm 620nm ^ λ 2 ^ 690nm 750nm ^ λ 820nm The second region contains a first diffraction structure with a plurality of annular regions whose center is on the optical axis and provides a diffraction action to the First to -28- 200532679 (26) One of the luminous fluxes, each of the plurality of truncated regions of the first diffraction structure includes a step structure including a predetermined number of discontinuous portions and step portions The third region includes a second diffractive structure having a plurality of annular regions, the center of which is on the optical axis, providing a diffractive action to one of the first to third luminous fluxes, and having a first and a third diffractive structure. Structures with different projection structures, each of the plurality of annular regions of the second diffraction structure includes a step structure, the step structure includes a predetermined number of discontinuous portions and step portions, and the third region does not The second luminous flux and the third luminous flux among the first to third luminous fluxes passing through the third region and the light converging element are formed as convergent light spots on the information recording surfaces of the second and third optical discs. Preferably, the optical pickup device satisfies the following expression. 3 70nm ^ λ 1 ^ 440nm 620nm ^ λ 690nm 750nm ^ λ 820nm The first region contains the first diffraction structure and has a plurality of annular regions, which are on the optical axis and provide a diffraction action on the first to the first. Among the three luminous fluxes, one of the plurality of annular regions of the first diffraction structure includes a step structure, the step structure includes a predetermined number of discontinuous portions and step portions, and the second region includes a first A two-diffraction structure with a plurality of annular regions, the center of which is on the optical axis, provides a diffractive action on one of the first to third luminous fluxes, and has a structure different from the first diffraction structure '-29 -200532679 (27) each of the plurality of annular regions of the second diffraction structure includes a step structure 'the step structure includes a predetermined number of discontinuous portions and step portions' and the third region is not The second light flux and the third light flux among the first to third light fluxes passing through the third area and the light converging element are formed as convergent light spots on the information recording surfaces of the second and third optical discs. Preferably, the diffractive optical element is composed of an optical element, and an optical surface of the optical element includes a second region and a third region. _ Preferably, the diffractive optical element is composed of an optical element, and an optical surface of the element includes a second region, and the opposite optical surface includes a third region. Preferably, the optical pickup device satisfies the following expression. 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 ^ NA3 ^ 0.55 where NAI, NA2, and NA3 are the numerical apertures of the first, second, and third optical discs used for recording or φ reproduction, respectively. Preferably, the optical pickup device satisfies the following expression. 0.64 ^ NA1 ^ 0.65 0.64 ^ NA2 ^ 0.70 0.43 ^ NA3 ^ 0.55 where NAI, NA2, and NA3 are the numerical apertures of the first, second, and third optical discs used for recording or reproduction, respectively. In the present invention, "giving a diffraction action" or "providing a diffraction action" is equivalent to a case where the light flux passing through the diffraction structure satisfies the condition of Gragg -30- 200532679 (28), that is, the The diffractive structure generates light having a specific diffraction order number according to the wavelength of the incident light flux, and its absolute 値 is diffractive efficiency of 0 or more compared to other diffraction order numbers (including 0), and Especially light with a diffraction efficiency of 25% or higher. Further, in the present specification, a "light spot" is an incident light flux having a number of apertures that is not less than a preset number of light spots necessary for recording or reproduction on the information recording surface. For example, in the case of recording or reproducing CD, the spot light is to generate an incident luminous flux corresponding to a numerical aperture (0-0.43 or 0.45) higher than the numerical aperture necessary for recording or reproducing CD. Light with a wavefront chromatic aberration of 0.07A3rms. "Resulting spot light" refers to a light flux that provides an incident light flux characteristic when the incident light is incident on the information recording surface so that the incident light flux has the above-mentioned chromatic aberration. In this specification, "substantially no phase difference" or "providing substantially no phase difference" means that the phase shift caused by the staircase structure of the diffraction structure φ is within ± 0.2 7Γ through the light flux of the diffraction structure. within. The present invention can provide an optical pickup device having an optical element capable of performing appropriate aperture adjustment on three types of optical discs including a high-density optical disc using a DVD laser light source 'DVD and a CD. The implementation of the preferred embodiment of the present invention can be explained as follows with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing the proper execution of any one of the high-density disc HD (first disc), DVD (second disc), and CD (third disc) -31-200532679 (29) A structural diagram of the structure of the first optical pickup device PU 1 for recording and reproduction. In the optical specifications of the high-density optical disc HD, the first wavelength λ 1 is 408 nm, and the thickness of the first protection layer tl is 0.85. In the optical specifications of the DVD, the second wavelength is 65 8 nm. The thickness t2 of the second protective layer PL2 is 0.6 mm and the numerical aperture NA2 is 0.60. In the optical specifications of the CD, the third wavelength λ 3 is 7 8 5 nm, and the thickness t3 of the third protective layer PL3 p is The diameter is 1.2 mm and the NA3 series is 0.45. The individual recording densities (P1 to P3) of the first to third discs satisfy p3 < p2 < p1, and in the objective optical system OBJ which performs recording and / or reproduction of information on the first to third discs individually The magnifications (the first magnification M1 to the third magnification M3) satisfy M1 = M2 = M3 = 0. Meanwhile, the wavelength, the thickness of the protective layer, the aperture diameter, the recording density, and the magnification are not limited to those described above. The optical pickup PU 1 essentially consists of the following: an ultraviolet semiconductor laser LD1 (first light source) that emits a laser light flux (first luminous flux) with a wavelength of 40 8nm when performing recording and reproduction of information of φ high-density optical disc HD, When performing information recording and reproduction of DVD information, the red semiconductor laser LD2, which emits a laser light flux (second light flux) with a wavelength of 65 8nm, is the first one to receive the reflected light flux from the information recording surface RL1 of the high-density disc HD. A photodetector P Η 1 and the recording and reproduction of CD information emits an infrared semiconductor laser LD3 (third light source) with a laser light flux (third light flux) with a wavelength of 785 nm, and receives information records from a DVD The surface RL2 or the reflected light from the information recording surface of the CD 32- 200532679 (30) The second light detector PD2 of the luminous flux, which has the diffractive optical element L 1 on the morphological surface of the diffraction structure and the two sides Aspheric surface has objective lens optical system of element L2 which functions to converge the laser light flux transmitted through optical element L1 on information recording surfaces RL1, RL2 and RL3, respectively. OBJ, dual-axis actuator AC1, high-density optical disc HD number aperture HA aperture STO, first polarized beam splitter BS1 to BS4, first to first | lenses C0L1 to C0L3, beam expander EXP , The first sensing SEN1 and the second sensing lens SEN2. In this optical pickup device PU1, when recording and reproduction is performed on a high-density optical disc, an ultraviolet semiconductor laser LD1 is irradiated (as shown by a solid line as its light path). The light flux emitted from the ultraviolet semiconductor laser is converted into a parallel light flux by the first alignment lens C0L1 and transmitted through the first polarized beam splitter BS1, and then transmitted through the expander EXP and the second polarized beam splitter BS2. The transmission 0 aperture ST0 is adjusted by the luminous flux diameter, and is spotted by the objective optical system OBJ on the information recording surface RL1 through the first protection. This objective optical system OBJ performs focusing and tracking with a two-axis actuator AC1 built around the objective optical system '. The reflected light flux from the information pit on the information recording surface RL1 passes through the objective optical system OBJ, the second beam splitter BS2, and the beam expander EXP again, and is then reflected by the first beam splitter BS1, after which Astigmatism by the sensing lens SEN 1), and the light receiving table at the first photodetector PD 1 is formed by the light lens having converged by the diffracted light corresponding to the amount of LD1 to the fourth to third alignment lens HD shown in Figure 1 Later, the astigmatism of the polarized light is modulated by the light beam and then by the layer PL1 to form a unified OBJ (face-33-200532679 (31) is converted by the third alignment lens COL3 into a convergent luminous flux. Therefore It can read the recorded information on the high-density optical disc HD by using the output signal of the first photodetector PD1. When the recording and reproduction of the information of the DVD is performed, the red semiconductor laser LD2 is first irradiated. The divergent light flux from the red semiconductor laser LD2 passes through the third polarized beam splitter and the fourth polarized beam splitter (the light path is shown in the dashed line in Figure 1), and is converged by the second alignment lens | COL2 Is a parallel light flux. After that, the light flux is reflected by the second beam splitter BS2 and forms a light spot on the information recording surface RL2 via the second protective layer PL2 by the objective optical system OBJ. The objective optical system OBJ is constructed by The biaxial actuator AC 1 around the objective optical system OBJ performs focusing and tracking. The reflected light modulated by the information pit on the information recording surface RL2 passes through the objective optical system OBJ again and is reflected at the second pole. The beam splitter BS2 is converted, and the rear mirror is converted into a convergent light flux by the second alignment lens C0L2, and is reflected by the fourth polarized φ beam splitter BS4, and then astigmatized by the second induction lens SEN2 and converged. On the light receiving surface of the second photodetector PD2. Therefore, it can use the output signal of the second photodetector PD2 to read the information recorded on the DVD. When the recording and reproduction of the information of the CD is performed, The infrared semiconductor laser LD3 is irradiated. The divergent light flux emitted from the infrared semiconductor laser LD3 is reflected by the third polarized beam splitter, and passes through the fourth polarized beam splitter ( Figure 1 shows its light path), and the second alignment lens C0L2 converges into a parallel light flux. After that, the light flux is reflected by the second beam -34- 200532679 (32) divider BS2, and passes through the third protection A layer PL3 is formed on the information recording surface RL3 and a light spot is formed by the objective optical system OBJ. The objective optical system 0BJT performs focusing and tracking with a two-axis actuator AC1 constructed around the objective optical system OBJ. The reflected light flux modulated by the information pit on the recording surface RL3 passes through the objective optical system OBJ again, and is reflected by the second polarized beam splitter BS2, and then converted by the second alignment lens C0L2 into a convergent light flux, and is converted by the first The four-lens lens B COL2 reflects and is then astigmatized by the second sensor lens SEN2 and converges on the light receiving surface of the second photodetector PD2. Therefore, it can read the information recorded on the CD by using the output signal of the second photodetector PD2. Next, the structure of the objective optical system OBJ is explained. The diffractive optical element L1 is a plastic lens, and its diffractive index nd for the d line is 1.5 09 1, the number of Abbe yd is 56.5, and the diffractive index of 11 is 1.5064, and the diffraction of λ 3 is The rate is 1.5 05 0. The light converging element L2 is a plastic lens φ, and its diffraction rate for the d-line is 1.5 43 5 and the number of Abbe ν d is 5 6 · 3. Meanwhile, although the drawing is omitted, the optical function portion (the area for diffractive optical element L 1 through which the first light flux passes and for the light converging element L 2) has a flange portion around it, each Each of the flange portions is individually combined with each optical function portion, and the optical function portion is firmly bonded when one portion of each flange portion is connected to the other flange portion. At the same time, when the diffractive optical element L1 and the light converging element L2 are firmly combined, it can also be combined via a lens frame which is another 'member. -35- 200532679 (33) The optical surface (incident surface) of the diffractive optical element L 1 that is closer to the semiconductor laser light source is divided into concentric circular forms that seal each region having NA 3 centered on the optical axis The first area AREA1 including the optical axis and the optical axis L is a concentric circular form corresponding to each area having a center in NA2 on the optical axis and is formed on the side of the first area AREA 1 and is provided with a first The second area AREA1 of the diffractive structure 10 and the third area AREA3 of the concentric circular shape corresponding to the area within NA 1 and formed outside the first area g AREA and equipped with the second diffractive structure 20 Meanwhile, when the aperture diameter of the BD or HD DVD is larger than the aperture diameter of the DVD, it satisfies fl X ΝΑΙ > f2 χ NA2 > f3 x NA3, and it is preferable to give a diffraction action to the second luminous flux passing through the third region. In the above expressions, each f 1, f2, and f3 represents the focal length of the objective optical element for each φ wavelength, and each NA, NA2, and NA3 represents necessary for recording or reproducing each optical disc. Number of apertures. The opening apertures NAI, NA2, and NA3 of the above structure satisfy, for example: 0.75 ^ NA1 ^ 0.90 0.60 ^ NA2 ^ 0.70 0.43 ^ NA3 ^ 0.55. Furthermore, the structure having the opening apertures NAI, NA2, and NA3 -36- 200532679 (34) satisfies the following Expression. 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 ^ NA3 ^ 0.55 When the aperture diameter of a DVD is larger than the aperture diameter of a BD or HD DVD, f2 X NA2 > fl X ΝΑΙ > f3 χ NA3 p The first luminous flux in the third region performs diffraction. In the above expressions, each of Π, f2, and f3 represents the focal wavelength of the objective optical element for each wavelength, and each NA, NA2, and NA3 represents the The number of paths necessary to record and reproduce each disc. The opening apertures NAI, NA2, and NA3 of the above structure satisfy the expression. • 0.64 ^ ΝΑ1 ^ 0.65 0.64 ^ ΝΑ2 ^ 0.70 0.43 ^ ΝΑ3 ^ 0.55 For the first diffractive structure 10 and the second diffractive structure 2 0, it has a ring region 13 formed by periodically forming a concentric circle. Structure, each concentric circle has a center on the optical axis L, and has a step structure (step structure) formed by a predetermined amount of step portions 11 and discontinuous portions 12 (see FIG. 3 (a) and FIG. As shown in 3 (b)) (hereinafter, this diffractive structure is called "diffraction structure HOE"), a ring-shaped area is directly made by each ring and each step is wound under the hole -37- 15 200532679 (35) The structure is structured and has the form of a partial diagram including a zigzag-shaped optical axis L (as shown in Figs. 4 (a) and 4 (b)), and its direction system and effective diameter direction by the step portion 16 A structure composed of a plurality of annular regions 17 that are the same and have the form of a partial diagram including a stepped optical axis (as shown in FIGS. 5 (a) and 5 (b)). In the meantime, each of the systems of Figs. 3 (a) to 5 (b) shows the structure of each diffraction structure formed on a plane and each diffraction structure, and each diffraction structure can also be formed on a spherical surface. On or aspheric. In this embodiment, the first diffractive structure 10 formed on the second area AREA2 and the second diffractive structure 20 formed on the third area AREA2 may be composed of the diffractive structure HOE (see FIG. 3 (a ) And 3 (b)) 〇 In particular, by establishing the level differences d 1 and d2, the number of discontinuous parts M1 and M2, to satisfy 4.8 X d ^ dl ^ 5.2 xd, 2 ^ M1 ^ 4 1.9 xd ^ d2 ^ 2.1 xd? 4 ^ M2 ^ 6 and each Ml and M2 is 2. When nl represents the diffraction rate of the diffractive optical element L 1 of wavelength λΐ, d 1 represents the optical axis in the first diffraction structure. The depth of the step portion, M 1 represents the number of discontinuous portions (integer), d2 represents the depth of the step portion in the optical axis direction in the second diffraction structure 20, and M2 represents the number of discontinuous portions (integer) ) And d = Al / (nl-l). When the first luminous flux having a wavelength λ 1 and the second luminous flux having a wavelength λ 2 enter the first diffraction structure, the step portion in the direction of the optical axis -38-

200532679 (36) Depth d 1 and the number of discontinuous parts M 1 When the above range of bond history is generated, it produces an 'optical path difference' whose sequence is λ 1 (microns) and λ 2 ( Micrometers), and the first luminous flux and the second luminous flux are not different. Therefore, the light flux is transmitted without diffraction and enters the light L2 (which is referred to as "zero-order diffraction light"). In order to record and reproduce the information of the CD ', the light flux passing through the third area AREA1 is used. Therefore, the third luminous flux of the second area AREA2 provided by the radiation structure 10 is 1 light. Therefore, the diffraction action is obtained by the first diffraction structure 10, and the third luminous flux passing through the first diffraction structure 10 does not converge on the treasure surface RL3, and thereby, it has a different order generated) The diffracted light having a relatively high diffraction efficiency (for example, more) among the diffracted lights becomes a light spot. At the same time, in some cases, multiple diffracted light (for example, + 1-dimensional diffracted light and -1-dimensional diffracted light) (approximately 40%). At this time, all of the majority of the diffracted diffracted light on the right information gB recording surface RL3 becomes a light spot with high diffraction efficiency. Further, when the first luminous flux having a wavelength λ 1 enters the structure 20 ′, where the depth of the step portion in the direction of the optical axis and the number of subsequent portions M 2 pass through the bond history to satisfy the above range, an optical path difference, which is Is a multiple of (micron) between adjacent step structures, and the first luminous flux does not substantially give a phase. Therefore, the luminous flux is transmitted and the zero-order diffracted light reaches the light and it is satisfied that it is a multiple of the adjacent number to the phase. Concentration of the first winding in the flux of the element, which makes the recording of factors (30% or several diffractions such as large CDs, diffracted light, second diffraction and non-continuous generation, the number λ 1 difference. Convergence element • 39- 200532679 (37) L2. Furthermore, in order to record and reproduce information on DVDs and CDs, the second luminous flux and the third luminous flux passing through the third area AREA3 (where the second diffraction structure 20 is provided) become unnecessary light. Therefore, The diffraction action is obtained by the second diffraction structure 20, so that the second light flux and the third light flux passing through the second diffraction junction 20 do not individually converge on the DVD and the information recording surfaces RL2 and RL3, but borrow Therefore, there is a relatively high diffraction efficiency (such as 30% or more) between the diffracted rays, and the resulting diffracted rays become spots. At the same time, in some forms, most of the diffracted rays ( For example, +1 and therefore diffracted light and -1 factor diffracted light have the same diffractive performance (for example, about 40%). At this time, all diffracted light with high diffractive performance or not on the information recording surface of DVD and CD The converged diffracted lights on RL2 and RL3 become light spots. At the same time, the first to third light fluxes do not circulate through the first area AREA 1 and pass through them. Φ, then pass the first to third light fluxes of the first area AREA 1 After passing through the diffractive optical element L1, the light converging element L2 is then subjected to the radiating action, and individually converged light spots are formed on the information recording surface of a prescribed optical disc. Further, the first and the first passing through the second area AREA2 are provided. The two fluxes pass through the diffractive optical element L1, and thereafter, are subjected to the diffractive action in the light converging element L2, and individually form a convergent light spot on the information recording surface of the prescribed optical disc. Further, the first area passing through the third area ARE A 3 Luminous flux After having the first structure, the CD shooter has a recorded amount of winding light, and then passes through -40-200532679 (38) to irradiate the optical element L1, and then receives the diffraction action in the light converging element L2, and in the high-density optical disc A convergent light spot is formed on the information recording surface. In this embodiment of the diffractive optical element L 1, the optical surface S 1 (incident surface) on the semiconductor laser light source is divided into a first area ARE A1 to a third The area AREA A3 is formed, and the first diffraction structure 10 is formed in the second area AREA2, and the second diffraction structure 20 is formed in the third area AREA3. However, it can separate the incident surface S1 into a first area | AREA1 and a second area AREA2, and form a first diffraction structure 10 in the second area AREA2 and a third area ARE A 3 on the optical surface S2 (producing surface) A diffraction structure 20 is formed on the third area AREA3 (as shown in FIG. 6), but it is not limited thereto. When the first diffractive structure 10 and the second diffractive structure 20 are separately provided on different optical surfaces, it is preferable that the depth d 1 in the step portion of the optical axis direction of the first diffractive structure 10 is not The number of consecutive parts M 1 (. Integer), the depth φ d2 of the step part in the optical axis direction of the second diffraction structure 20, and the number of discontinuous parts 部分 M2 (integer) are in the following range: 4.8 X d 'dl S 5.2 X d, 2 $ Ml S 4 0.9xd ^ d2 ^ 1.1xd? M2 = 2 As shown in this embodiment, by forming a second region AREA2 on which the first diffraction structure 10 is formed, and The second diffractive structure 20 is formed in the third area ARE A3 of the same optical surface (for example, the incident surface) of the diffractive optical element L1, which can provide corrections for chromatic aberrations caused by different wavelengths between the light fluxes, respectively. The structure of chromatic aberration and the structure used to change the spherical aberration caused by temperature changes (on the surface of protrusion -41-200532679 (39)). In the optical pickup device PU1 shown in this embodiment, the first diffractive structure 10 is formed in the second area AREA2 corresponding to NA2, and the second diffractive structure 20 is located in the area corresponding to the inner side of NA1. The third luminous flux passing through the first diffraction structure 10 and the second diffraction structure 20 becomes a light spot member, which forms a light spot on the information recording surface of the CD, so that the objective optical element OBJ has an aperture adjustment function relative to NA3. . B Further, the second light flux passing through the second diffractive structure 20 becomes a light spot member, which causes a light spot to be formed on the information recording surface of the DVD, which makes the objective optical element OBJ have an aperture adjustment function with respect to NA2. In the optical pickup device compatible with the three types of optical discs, it does not require the use of a beam splitter or a liquid crystal phase control element as the aperture adjustment mechanism, so it can maintain a reduction in the manufacturing cost of the optical pickup device. ? (Second Embodiment) The structure of the optical pickup device in this embodiment is substantially the same as that of the first embodiment, except for the structure of the diffractive optical element L1 explained below. The incident surface S 1 of the diffractive optical element L 1 is divided into a first area AREA1 in the form of a concentric circle. Each concentric circle has its center on the optical axis of the area corresponding to NA3, and includes the optical axis and the first A diffractive structure 10, a second area AREA2 in the form of a concentric circle, each centered on an optical axis L corresponding to the area inside NA2, and formed in a region outside the first area AREA1 and having a second The diffractive structure 20 and the third area AREA3 in the same circle shape as -42- 200532679 (40), each centered on the optical axis L corresponding to the area within NA1 and formed in the first area AREA 1 Outside area. The second area AREA2 is further divided into 2A areas in the form of concentric circles, the center of each concentric circle is on the optical axis L and is closer to the optical axes L and 2B areas far from the optical axis, and the second area formed in the 2A area The diffractive structure 20 is a second diffractive structure 20 formed on a 2B area designed to be different from each other. In particular, the diffractive structure HOE of the structure shown in FIG. 3 (a) and FIG. 3 (b) is formed by each of the first diffractive structure 10 and the second diffractive structure 20, and when nl Represents the diffraction rate of the diffractive optical element L 1 at the wavelength λΐ, d 1 represents the depth of the step portion in the optical axis in the first diffraction structure 10, M 1 (integer) represents the number of discontinuous portions, and d 2 Represents the depth of the step portion in the direction of the optical axis in the second diffraction structure 20, and M2 (integer) represents the number of discontinuous portions, the level difference dl and φ d2, and the number of discontinuous portions M 1 and M2 After the establishment of the case, it is also 1 / (nl-l), so that 1.9 X d ^ dl ^ 2.1 X d? 4 ^ M1 ^ 6 0.9 x d2 ^ 1.1 xd, M2 ^ 5 and Ml is 5, in 2A The M2 in the area is 3, and the M2 in the 2B area is 5, as shown in FIG. 7. When the first luminous flux with a wavelength λΐ and the third luminous flux with a wavelength λ3 enter the first diffractive structure 10, the depth d1 of the step portion in the optical axis direction and the number of discontinuous portions M1 are established such that -43- (41) (41) 200532679 satisfies the above range, which produces an optical path difference, which is essentially a multiple of an integer of λ 1 (microns) and λ 3 (microns) between adjacent step structures, There is no phase difference between the first luminous flux and the third luminous flux. Therefore, the light flux is transmitted without diffraction, and the zero-order diffraction light reaches the light converging element L2. On the other hand, when the second luminous flux having a wavelength λ2 enters the first diffraction structure 10, the second luminous flux is diffracted by an optical path difference between adjacent stepped structures, and has a comparison between the second luminous fluxes. Diffraction light with high diffraction efficiency converges on the information recording surface of DVD. When a first light flux having a wavelength λ 1 enters the second diffraction structure 20, the depth d2 of the step portion in the optical axis direction and the number of discontinuous portions M2 are established so that it can satisfy the above range, which An optical path difference is generated, which is substantially a multiple of an integer of λ 1 (micrometers), and the first luminous flux has a substantially phase difference. Therefore, the light flux is transmitted and reaches the light converging element L2 with zero-order diffraction light. On the other hand, when the second light flux with a wavelength λ2 and the third light flux with a wavelength λ3 are incorporated into the second diffractive structure 20, the second light flux and the third light flux are generated between adjacent stepped structures. Diffraction by the optical path difference, while the diffraction light with the highest diffraction efficiency between the second light flux is converged on the information recording surface RL of the DVD, and the diffraction light of the third light flux becomes a light spot, so that it is not converged on the CD Information on the surface. At the same time, the second luminous flux and the third luminous flux among the first to third luminous fluxes passing through the third area ARE A 3 are subjected to the diffraction action by the light converging element L2 -44-200532679 (42), whereby Become a light spot so that the two do not individually converge on the specified disc. After that, the first to third luminous fluxes passing through the first area AREA 1 pass through the diffractive optical element L1, and then the diffractive action is obtained in the light converging element L2, and are formed individually on the information recording surface of the prescribed optical disc Convergent light spot. Further, the first luminous flux and the p-th second luminous flux passing through the second area ARE A2 pass through the diffractive optical element L1, and then a convergence action is obtained in the light converging element L2, and each is formed on the information recording surface of a prescribed optical disc Convergent light spot. Further 'the first * luminous flux passing through the second area AREA3 passes through the diffractive optical element L i and then obtains a diffractive action in the light converging element L2' to form a convergent light spot on the information recording surface RL 1 of the high-density optical disc HD. In the optical pickup device shown in this embodiment, the first diffraction structure φ 10 is formed on the first area AREA 1 corresponding to NA3, and the second diffraction structure 20 is on the inside corresponding to NA2. Area, and the third luminous flux passing through the first diffraction structure 10 and the second diffraction structure 20 becomes a light spot member, which will not cause the formation of light spots on the information recording surface RL3 of the CD, which can make the objective lens The optical element OBJ has an aperture adjustment function relative to NA3. Further, the second light flux passing through the third area ARE A3 becomes a light spot member, which does not cause a light spot to be formed on the information recording surface RL2 of the DVD, which makes the objective optical element OBJ have a hole relative to NA2-45- 200532679 ( 43) diameter adjustment function. Therefore, it is not necessary to use a spectroscopic filter or a liquid crystal phase control element as the diameter adjustment mechanism in an optical pickup device compatible with three types of optical discs, and thus the manufacturing cost of the optical pickup device can be reduced. The second area AREA2 is divided into The shape p of the second diffractive structure 20 including the 2A area and the 2B area is the same as that of the second diffractive structure 20 formed in the 2B area. Therefore, the vertical spherical aberration of the third light from the first area AREA 1 to 2A area becomes discontinuous. Therefore, it can improve the improvement of the detection of the reflected light of the third light flux of the second optical device PD2. The 2A area can also be provided on the surface of the protruding body S2. However, the longitudinal spherical aberration of the third light from the AREA 1 to 2A areas of the first area is discontinuous, and it can be used for the second light detector. Improved the detection of the reflected light of the three luminous flux. φ At the same time, the structure of the optical pickup device is not limited to that shown in Fig. 1 and can be freely modified to the structure shown in Fig. 8. The optical pickup device PU2 shown in FIG. 8 is composed of a laser module LM1 of a high-definition disc HD and a DVD (consisting of: a first ejection point EP 1 (first light source), which performs recording and reproduction of a high-density disc And emit a laser light flux with a wavelength of 408nm (first light flux, second light emission point EP2 (second light source), which emits a laser light flux with a wavelength of 6 5 8 nm when performing DVD recording and reproduction information ), The first light-receiving part DS 1, which receives from high density, which is a hole descending domain, is a system of mutual flux detection 0, and the flux PD2, and the density is a photometric photo) (the first light • 46- 200532679 (44) The reflected light flux of the information recording surface RL 1 of the disc HD, the second light receiving part DS2, which receives the reflected light flux of the information recording surface RL2 of the DVD, and a diamond mirror), the module MD1 of the CD, of which When performing CD recording and reproduction information, the infrared semiconductor laser light LD3 (third light source) with a laser light flux (third light flux) with a wavelength of 7 8 5nm is emitted and the light detector PD3 is firmly combined. The objective lens optical system is O The BJ system is composed of an aberration correction element L 1 of p formed with a diffraction structure as a phase structure on an optical surface, and a light converging element L 2 having an aspherical surface on both sides thereof, and having a transmission path in an information record. The function of converging the laser light flux on each of the surfaces RL1, RL2, and RL3. The biaxial enabler AC1 and the uniaxial enabler AC2 correspond to the partition STO of the high-density optical disc HD and the aperture NA1. A beam splitter BS, an alignment lens C0L, a coupling lens CUL, and a beam shaping element SH. In this embodiment described above, the diffractive optical element is a part constituting the optical element of the objective lens. However, the diffractive optical element may be configured to be separated from the objective optical phi element, and is not limited to the above. Further, in the above-mentioned embodiment, it may be best considered that the optical surfaces (incident surface S1 and protrusion surface S 2) of the diffractive optical element L1 are in the form of a plane, and in the step portion of the optical axis direction, The depths d 1 and d 2 are within the above-mentioned crimes (when the first diffraction structure 10 and the second diffraction structure 20 are formed on the optical surface in a planar form. However, they may also form the first diffraction The structure 10 and the second diffractive structure 20 are on the optical surface of a spherical surface or an aspherical surface (as described above), and when the optical surface of the diffractive optical element L1 is at a predetermined angle with the incident light or -47- 200532679 (45) When tilted more (for example, '10 degrees or more), it can be designed so that the optical path length of the light flux entering the di-diffractive structure 10 and the di-diffractive structure 20 is about dl Within the above range of d2. Example Next, Example 1 is explained below. In this example, the optical pickup device shown in FIG. 1 is used as the incident surface (first surface) of the diffractive optical element shown in FIG. 6. Split into first area AR EA1 (the height h with the optical axis satisfies 0.00mm S h $ 1.27mm) and the second area AREA A2 (1.27mm $ h), and the first diffraction structure is formed in the second area AREA2 and the third area AREA3 ( 1.6 mm 5 h) is the protrusion surface (second surface 0) of the diffractive optical unit, and the second diffractive structure is formed in the third area ARE A3. At the same time, the first area AREA1 is diffractive With respect to each of the first diffraction structure and the second diffraction structure, 'which forms a diffraction structure HOE, in which a concentric circular ring-shaped region is formed periodically', each center of which is on the optical axis and has A step structure made up of a specified number of step parts and discontinuous parts (as shown in Figures 3 (a) and 3 (b)). -48- 200532679 46

η · 8 / τι " εςΓ \ 1 · ετ / τΛ 白 οπε0ς · 0 = ενΝ ς9 · 0 = ζνΝ S · ΟΛνΝ sf «>« _8ε · νΜ7 震 卜 00 · 3 = ^ 圆 0〇〇.7 heart fes «51« 1 丨 1 Skimming diffraction surface Diffraction surface Aspheric surface Aspheric surface ni (785nm) I 1.5111 I 1.0000 1.6002 1.0000 I 1.5704 I di (785nm) 20.64962 1.00000 0-10000 2.50000 0.51117 1.20000 ni (655nm) 1.51436丨 1.00000 I | 1.60423 | I 1.00000 I | 1.57721 I i di (655nm) 32.60744 1.00000 0.10000 | 2.50000 | 0.76461 0.60000! Ni (407nm) | 1.52994 | | l.ooooo | | 1.62417 | | 1.00000 | | 1.61869 | di (407nm ) 8 | 1.00000 | 0.10000 | 2.50000 | | 0.84612 | 0-10000 M 8 8 1.58727-5.93291 8 8 璧) s mM ο Η (NJ 00 L〇KD 蛏 酲 * N® «(I. ±) 1 Pelican «I16 * IP Dim + -49- (47) 200532679 Table 1-2 Diffraction data First surface 0.0mm < h < 1.27mm Non-diffraction surface 1.27mm < h Coefficient of optical path difference function B2 4.58000E + 00 * Number of non-continuous parts of each diffractive ring zone = amount of 2 level difference = 5χ407 / 0 · 53ητη (with 5χ wavelength 407nm Amount of level difference of optical path difference) Second surface 0.0mm < h < l.635mm Non-diffractive surface 1.635mm < h Coefficient of optical path difference function B2 4.58000E + 00 * Negative of each diffraction annular region Number of consecutive parts = 2 quasi-difference amount = 4x407 / 0.53nm (amount with quasi-difference of optical path difference of 2x wavelength 407nm) Aspheric surface data Third surface aspherical surface coefficient κ -6.70012E-01 A4 8.07946E-03 A6 6.72041E-04 A8 -4.91558E-05 A10 3.14894E-04 A12 -9.03986E-05 A14 -7.00670E-06 A16 1.10458E-05 A18 -1.80902E-06 Fourth surface non-spherical surface Coefficient κ -2.56348E + 02 A4 3.05938E-02 A6 -1.26555E-03 A8 -8.74183E-03 A10 3.51990E-03 A12 -3.84247E-04 A14 -1.98538E-05 -50- 200532679 (48) in the table In 1-1 and 1-2, ri represents the radius of curvature, di represents the interval from the first surface to the (i + I) th surface, and ni represents the diffraction rate of each surface. As shown in Tables 1-1 and 1-2, when the wavelength emitted from the first light source is again; [in the case of 40 7nm, the focal length fl is set to 2.30 mm, and the number of image sides 値 aperture NA 1 is 0 · 8 5 'and the imaging magnification m is 0, in the case of a wavelength of 6 5 5 nm emitted from the second light source, the focal length g f2 is set to 2.37 mm, the number of image sides 値 aperture NA2 is set to 0.65, and the imaging The magnification m is set to -1 / 13.25 'and the focal length f3 is set to 2.38mm when the wavelength λ3 emitted from the third light source is 78 5nm, the number of image sides 値 aperture NA3 is set to 0.5, and The imaging magnification m is -1 / 8.14 (in the optical pickup device in this example). Further, the number 値 M1 of the discontinuous parts in the first diffraction structure is 2, and the number 値 M2 in the discontinuous parts of the second diffraction structure is 2. The incident surface (first surface) and protruding surface (second surface 0) of each diffractive optical element and the incident surface (the Ξ surface) and the protruding surface (the fourth surface) of the light converging element are formed as Non-spherical surfaces are specified by the expression 値, where the coefficients shown in Tables 1-1 and 1-2 are replaced by 个别 1, and rotationally symmetric to the optical axis. (数 値 1) = — ^ And) —a + l + Vl- (l + / c) (A / i?) 2 / = 0 In the above expression, x (h) represents the axis in the direction of the optical axis (the direction of light travel is positive) , / C represents the conic constant, and A2i represents the coefficient of the non-spherical table-51-200532679 (49) plane. Each luminous flux having a wavelength given by each of the first diffractive structure and the second diffractive structure is specified by a mathematical expression, wherein the coefficients shown in Tables 1 _ 1 and 1-2 are expressed by numbers The optical path difference function of 値 2 is replaced. (Number 2) Φ (^) = y] B2ih / = 0 In the above expression, B2i represents the coefficient of the optical path difference function. The depth d 1 of the step portion in the direction of the optical axis in the first diffraction structure is established to obtain an optical path difference of a wavelength equal to λ 1 x5. Therefore, an optical path difference of about 3 wavelengths is given to a wavelength λ 2 The second luminous flux and the amount of phase change are relatively small for the first luminous flux having a wavelength of λ 1 and the second luminous flux having a wavelength of λ 2 without causing a diffraction action. Only for the third luminous flux with a wavelength of λ 3, a phase difference equal to about 0.5 wavelength (7Γ) is obtained, and a diffraction action occurs. The depth d2 of the step portion in the optical axis direction of the second diffractive structure is established such that an optical path difference equal to λ 1 x4 is obtained. Therefore, an optical path difference approximately equal to 2 wavelengths is given to the second luminous flux. However, for The amount of phase change of the first light flux and the third light flux is relatively small, and no diffraction action occurs. Only for the second luminous flux, a phase difference of about 0.5 wavelength (7Γ) is obtained, and a diffraction action occurs. FIG. 9 shows longitudinal spherical aberration diagrams for the first luminous flux (BD), the second luminous flux (DVD), and the third luminous flux (CD), respectively. Figure 9 shows that the longitudinal spherical aberration is controlled for the necessary number of apertures of all the first to third luminous fluxes 200532679 (50), and the height of the longitudinal spherical aberration from the optical axis exceeds the necessary number of apertures. The area is discontinuous, and the objective optical system has excellent aperture adjustment functions for the second and third luminous fluxes. Next, an example 2 is explained below. In this example, the optical pickup device shown in FIG. The incident surface (first surface) of the diffractive optical element shown in 7 is divided into a first area AREAl (0.00mm $ h < 1.17mm), a 2A area (1.17mm ^ h < 1.44), and a 2B area (1.44 $ h < 1.54mm) and the third area AREA3 (1.54 $ h) and the first diffraction structure is formed on the first area AREA1, and the second diffraction structure is formed on each of the 2A and 2B area. At the same time, the third area ARE A3 is a diffraction interface. Further, the incident surface and the projection surface of each of the diffractive optical elements are planar surfaces. For each of the first diffraction structure and the second diffraction structure, the system φ forms a diffraction structure Η Ο E, where the system forms a concentric circular ring-shaped region, each centered on the optical axis. , Which has a step structure composed of a predetermined amount of step parts and discontinuous parts (as shown in Figure 3 (a) and 3 (b)). The lens data is shown in Tables 2-1 and 2-2. -53- Q: (51) 200532679 Huo 0SSM «¥ i« ^ τ · 8 / τ 丨 ΗLOK0 = s tremor 8PO · νη3: one S9.0 = C \ JVN noodles ε. ≪ Ν = ^ one so = IVN function οεζ = ^ Diffraction surface Diffraction surface Non-spherical surface Non-spherical surface i ni (785nm) I 1.5111 1 1.0000 1.6002 1.0000 1.5704 di (785nm) 20.40952 1.00000 0.10000 2.50000 0.51456 1.20000 ni (655nm) | 1.51436 I 1.00000 1 1.60423 1 1.00000 1.57721 di (655nm) 8 1.00000 0,10000 2,50000 0.58350 0.60000 ni (407nm) | 1.52994 | 1.00000 1.62417 1.00000 | 1.61869 | di (407nm) 8 1.00000 0.10000 2.50000 0.84612 0.10000 -H 8 8 1.58727 -5.93291 8 8 o rH CM ro LO Wake up * Ns * (Ii) city WH® * 丨 tear ffille «ip shame you. -54- (52) 200532679 Table 2-2 Diffraction data first surface 0.0mm < h < 1.17 mm * Number of coefficients of the optical path difference function of the discontinuous part of each diffractive ring zone = 5 B4 -5.4454E-04 Amount of level difference = 2x407 / 0.53nm B6 -6.1686E-05 (with 2x wavelength 407nm optical path B8 -1.4718E-05 difference in level) 0.17mm < h < l.44mm * Each diffraction ring Number of coefficients of the optical path difference function of the discontinuous part = 3 B4 -5.4454E-04 Amount of level difference = lx407 / 0.53nm B6 -6.1686E-05 (optical path with 1 X wavelength 407nm B8 -1.4718E -05 The amount of difference in level) 1.44mm < h < 1.5mm * The number of coefficients of the optical path difference function of the discontinuous part of each diffractive ring zone = 5 B4 -5.4454E-04 Amount = 2x407 / 0.53nm B6 -6.1686E-05 (the amount of difference between the optical path B8 -1.4718E-05 with 2x wavelength 407nm) 1.54mm < h Non-diffraction surface non-spherical surface data third surface Four-surface non-spherical surface coefficient K -6.70012E-01 A4 8.07946E-03 A6 6.72041E-04 A8 -4.91558E-05 A10 3.14894E-04 A12 -9.03986E-05 A14 -7.00670E-06 A16 1.10458E-05 A18 -1.80902E-06 Aspheric surface coefficient K -2.56348E + 02 A4 3.05938E-02 A6 -1.26555E-03 A8 -8.74183E-03 A10 3.51990E-03 A12 -3.84247E-04 A14 -1.98538E-05 -55- 200532679 (53) As shown in Tables 2 -1 and 2 -2, the focal length Π is set to 2.30 mm when the wavelength emitted from the first light source is 1 40 7nm. The number of image sides, the aperture NA, 1 is 0.85, and the imaging magnification m is 0. In the case where the wavelength emitted from the second light source is 6 5 5 nm, the focus length is set to 2.37 mm, and the number of image sides値 The aperture NA2 is set to 0.85, and the imaging magnification m is set to -W13.25, and the focal length f3 is set to _ 2.3 8mm when the wavelength emitted from the third light source; I 3 is 7 8 5 nm The image side number / aperture NA3 is set to 0.45, and the imaging magnification m is -1 / 8.14 (in the optical pickup device in this example). Further, the number of discontinuous parts in the first diffraction structure 结构 M 1 is 5, the number of discontinuous parts in the 2A area between the second diffraction structures 値 M2 is 2, and the discontinuity in the 2B area is 2 The number of parts 値 M2 is 5. The incident surface (third surface) and the protrusion surface (fourth surface) of each of the light converging elements are formed as non-spherical surfaces. The spherical surface is defined by a mathematical expression, in Table 2-1 and The φ coefficients shown in 2-2 are individually replaced by the number 値 1. The optical path length given by each of the first and second diffractive structures to each luminous flux with each wavelength is specified by a mathematical expression, where Tables 2-1 and 2-2 The coefficient is replaced by an optical path difference function of the number 値 2. The depth d 1 of the step portion in the direction of the optical axis in the first diffraction structure is established so that the optical path difference to a wavelength equal to λ 2x2, and therefore, the optical path difference equal to about 1 wavelength is given to the third luminous flux, Therefore, the phase change brightness is small for the first luminous flux and the third luminous flux, without -56- 200532679 (54) causing a diffraction action. Only for the second luminous flux, a phase difference equal to about 0.2 wavelength (0.47Γ) is obtained, and a diffraction action is generated. The depth d2 of the step portion in the direction of the optical axis in the second diffraction structure in the 2 A region is established so that an optical path difference equal to a wavelength of λ 1x1 is obtained. Therefore, the phase of the first light flux remains unchanged without Generates diffraction action. For the second luminous flux, a phase difference equal to about 0.4 wavelength (0.8 7Γ) is obtained, and for the third luminous flux, a phase | phase difference equal to about 0.5 wavelength (7Γ) is obtained, resulting in diffraction action. Further, the depth d2 of the step portion in the optical axis direction in the second diffraction structure 20 in the 2B region is established to obtain an optical path difference equal to λ 1 χ2, and therefore, an optical path difference equal to about 1 wavelength is obtained, Therefore, the phases of the first luminous flux and the third luminous flux remain unchanged, and no diffraction action occurs. For the second luminous flux, a phase difference equal to about 0.2 wavelength (0.4 7Γ) is obtained, and a diffraction action is generated. FIG. 10 is a longitudinal spherical aberration diagram for the first luminous flux (BD), the second luminous flux (φ DVD), and the third luminous flux (CD). Fig. 10 shows that the longitudinal spherical aberration is controlled by a numerical aperture necessary for all the first to third luminous fluxes, and the longitudinal spherical aberration is in a region where the height from the optical axis exceeds the required numerical aperture. Instead of continuous, the objective optical system has an excellent aperture adjustment function for the second and third light fluxes.接 者 'Example 3 is explained below. In this example, the optical pickup device shown in FIG. 1 is used to divide the incident surface (first surface) of the diffractive optical element shown in FIG. 11 into -57- 200532679 (55) an area ARAl (0.00mm 'h < 1.644mm), the second area AREA2 (1.644mm ^ h < 1.902mm), the third area A RE A3 (1.920 mm ^ h)' and the first diffraction structure 10 is formed in the first The second area AREA2 is above, and the second diffraction structure 20 is formed in the third area. At the same time, the first area AREA1 is a diffraction interface. For each of the first diffractive structure and the second diffractive structure, it forms a diffractive structure HOE, in which a concentric circular ring-shaped region is formed periodically, and each of its centers is on the optical axis, which has A step structure composed of a predetermined amount of step parts and discontinuous parts (as shown in Figures 3 (a) and 3 (b)). The lens information is shown in Tables 3-1 and 3-2.

-58- 200532679 (56)

Bu CNJ, Bu τ / τ- = 6 82 · 99τ / τι = ε s .38 / 1 = say »+ < w # 1s olo.ohpovnlo9-〇 = c \ 1vn 59 · 0 = τνΝ sfffls ε = ^ es.oonzj iLOo-ponTJ Secret 鋦 I_I-Sm Diffraction surface Aspheric surface Aspheric surface ni (785nm) 1 1.5035 1 1 l.oooo I 1.5372 1.0000 1.5704 di (785nm) O 00 KD- L〇 1.00000 0.10000 ί 1.87000 0.51746 1.20000 ni (655nm) 1 1.50673 1 | l.ooooo | 1.54073 1.00000 [1.57721 I di (655nm) L〇σ \ ro 1.00000 0.10000 1.87000 1.72623 0.60000 ni (407nm) 1 1.52491 1 11.00000 | 1.56013 1 1.00000 1 1 1.61949 | di (407nm) ooo L〇CM 1 0.80000 0.10000 1.87000 1.57967 1 0.60000 1 • H 8 8 1.92607 -9.84753 8 8 1® mm o \ ~ 1 CM ΡΟ LO SE:? H * (I. ±) paper m ® «—Paper" Long «Φ Shade You + -59- (57) 200532679 Table 3-2 Diffraction Data First Surface 0.0mm < h < l .644mm Non-diffraction Surface 1.644mm < h < l .902mm Optical Path Coefficient of function B4 -9.5828E-01 * Number of discontinuous parts of each diffractive ring zone = 2 amount of quasi-difference = 3x407 / 0.525nm (position with optical path difference of 1 X wavelength 407nm Amount of difference) 1.902mm < h Coefficient of optical path difference function B4 -9.5828E-01 * Number of discontinuous parts of each diffractive ring zone = 3 level difference amount = lx655 / 0.507nm (with 1 X-wavelength 655nm optical path difference level difference amount) Aspheric surface data Third surface aspheric surface coefficient n -0.766990 A4 4.96273E-03 A6 6.18596E-04 A8 -1.30980E-05 A10 2.12263E-05 A12 -2.29629E-06 Fourth non-spherical surface coefficient κ -4.51771E + 01 A4 9.72492E-03 A6 -2.00947E-03 A8 2.33032E-04 A10 -1.32931E-05 -60- 200532679 (58) As shown in the table As shown in 3 -1 and 3 -2, when the wavelength emitted from the first light source; I 1 is 407 nm, the focal length Π is set to 3.05 mm, the number of image sides 値 aperture ΝΑΙ is 0.65, and the imaging magnification is m is 1 / 82.64, in the case of a wavelength of 65 5 nm emitted from the second light source, the focal length f 2 is set to 3. 16 mm, the number of image sides 値 aperture NA 2 is set to 0.65, and the imaging magnification 17mm The rate m is set to -1 / 166.28, and the focal length f3 is set to 3. 17mm when the wavelength λ3 emitted from the third light source is 7 8 5 nm The number of image side apertures NA3 is set to 0.5, and the imaging magnification m is -1 / 17.27 (in the optical pickup device in this example) 〇 Further, the number of discontinuous portions in the first diffraction structure 値 Μ 1 Is 2 and the number of discontinuous parts 第二 M2 in the second diffraction structure is 3. The incident surface (third surface) and the protrusion surface (fourth surface) of each of the light converging elements are formed as non-spherical surfaces, and the spherical surface is specified by a mathematical expression, in Table 3-1 and The coefficients shown in 3-2 are individually replaced by the number 値 1. The length of the optical path given by each of the first and second diffractive structures to each luminous flux with each wavelength is specified by a mathematical expression, in Tables 3-1 and 3-2 The coefficient is replaced by an optical path difference function of the number 値 2. The depth d 1 of the step portion in the optical axis direction in the first diffraction structure is established so that the optical path difference to a wavelength equal to λ 1 x3, and therefore, the optical path difference equal to about 2 wavelengths is given to the third luminous flux. Therefore, the brightness of the phase change is small for the first luminous flux and the third luminous flux, and does not cause a diffraction action of -61-200532679 (59). Only for the second luminous flux, a phase difference equal to about 0.5 wavelength (π) is obtained, and a diffraction action is generated. The depth d2 of the step portion in the direction of the optical axis in the second diffraction structure in the second region is established so that an optical path difference equal to another 2x1 wavelength is obtained. Therefore, the phase of the second light flux remains unchanged without generating Diffraction action. For the first luminous flux, a phase difference equal to about 0.4 wavelength (0.8 7Γ) is obtained, and for the third luminous flux, a phase p phase difference equal to about 0.5 wavelength (7Γ) is obtained, resulting in a diffraction action. FIG. 12 is a longitudinal spherical aberration diagram for the first luminous flux (HD DVD), the second luminous flux (DVD), and the third luminous flux (CD). Figure 12 shows that the longitudinal spherical aberration is controlled by the numerical aperture necessary for all the first to third luminous fluxes, and the longitudinal spherical aberration is in the area when the height from the optical axis exceeds the required numerical aperture Instead of continuous, the objective optical system has an excellent aperture adjustment function for the second and third light fluxes. [Brief Description of the Drawings] FIG. 1 is a plan view of a main part of a structure of an optical pickup device. Fig. 2 is a side view of an example of a diffractive optical element. Figures 3 (a) and 3 (b) are side views of examples of diffractive optical elements. 4 (a) and 4 (b) are side views of examples of diffractive optical elements. Figures 5 (a) and 5 (b) are -62-200532679 (60) side views of examples of diffractive optical elements. Fig. 6 is a side view of an example of a diffractive optical element. Fig. 7 is a side view of an example of a diffractive optical element. FIG. 8 is a plan view showing a main part of the structure of the optical pickup device. FIG. 9 is a longitudinal spherical deviation diagram in Example 1. FIG. FIG. 10 is a longitudinal spherical deviation diagram in Example 2. FIG. Fig. 11 is a side view showing an example of a diffractive optical element. Figure 1 2 is a longitudinal spherical deviation diagram of Example 3. [Description of main component symbols] LD1: Ultraviolet semiconductor laser LD2: Red semiconductor laser LD3: Infrared semiconductor laser COL1: First alignment lens COL2: Second alignment lens φ COL3: Third alignment lens SEN1: No. An induction lens SEN2: a second induction lens BS1: a first polarized beam splitter BS2: a second polarized beam splitter BS3: a third polarized beam splitter BS4: a fourth polarized beam splitter PD1: First photodetector PD2: Second photodetector-63- 200532679 (61) PU1: First optical pickup device EXP: Beam expander STO: Aperture 〇BJ: Objective optical system AC1: Biaxial actuator RL1 , RL2, RL3: Information record surface PL1: First protective layer_PL2: Second protective layer PL3: Third protective layer L1: Diffractive optical element L2: Light converging element HD: High-density optical disc DVD: Digitally more Functional CD: Compact disc 1 〇: First diffraction structure φ 1 1: Step part 1 2: Discontinuous part 1 3: Ring area 1 5: Ring area 1 6: Step part 1 7: Ring zone 20: second diffraction structure PU2: optical pickup device EP1: first light exit point. / Γ -64- 200532679 (62) LM1: Laser module DS 1: First light receiving part DS 2: Second light receiving part AC1: Biaxial enabler AC2: Uniaxial enabler S Τ Ο: Shelf BS: Polarized beam Separator_ COL: Alignment lens CUL: Coupling lens MD 1: Module PD3: Photodetector

Claims (1)

200532679 (1) X. Patent application scope1. An optical pickup device for recording and / or reproducing information on the information recording surface of an optical disc with a protective substrate having a predetermined thickness, including: a first light source, emitting A first light flux having a wavelength λ 1 to record and / or reproduce information on the optical recording surface of a first optical disc with a protective substrate having a thickness t1; 0 — a second light source emitting a second wavelength λ 2 (λ 2 > λ1) The second light flux is used to record and / or reproduce information on the optical recording surface of the second optical disc with a protective substrate having a thickness t2 (t2gtl); a third light source having a wavelength λ3 (λ3 > λ2) The second luminous flux is used to record and / or reproduce information on the optical recording surface of the third optical disc with a protective substrate having a thickness t3 (t3 >t2); a diffractive optical element for transmitting the first to A third light flux; and an objective optical system having a light converging element to converge the first to third light fluxes passing through the diffractive optical element to the first to third optical discs, respectively Above, wherein the diffractive optical element includes a first region whose center is on an optical axis; a second region, which is formed outside the first region along a direction perpendicular to the optical axis and is formed in a ring shape, and includes A first diffractive structure; a third region, which is formed in a ring shape along the direction perpendicular to the optical axis, and includes a second diffractive structure; the first region will pass through the first A region and the first-66-200532679 (2) to third light fluxes of the light converging element are formed as convergent light spots on the information recording surfaces of the first to third discs respectively, and the second region will pass through the second region And the first and second luminous fluxes of the first to third luminous fluxes of the optical convergence element are formed as convergent light spots on the information recording surfaces of the first and second discs, respectively, and will not pass through the first area and the light. The third luminous flux among the first to third luminous fluxes of the converging element is formed as a convergent light spot on the information recording surface of the third disc, and the third region will pass through the third region and the light converging element. One of the first to third luminous fluxes is formed as a convergent light spot on the information recording surface of the corresponding disc between the first and second discs, and does not pass The third region and the third luminous flux among the first to third luminous fluxes φ of the light converging element, and the first luminous flux and the second luminous flux of the other are corresponding between the first to third discs. The information recording surface of the disc is formed as a convergent light spot. 2. The optical pickup device according to item 1 of the application, wherein the diffractive optical element includes an optical unit, and an optical surface of the optical element includes a second region and a third region. 3. The optical pickup device according to item 1 of the patent application range, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a first region 'and the opposing optical surface includes a third region. -67- 200532679 (3) 4. If the optical pickup device according to item 丨 of the patent application scope, the ~ diffraction structure provides a diffraction action for the third light flux passing through the second area, and the β ~ diffraction structure Another diffraction action is provided for the second luminous flux and the first luminous flux passing through the third region. 5 · If the optical pickup device of the patent application item 4 satisfies the following expressions: • fl X ΝΑ1 > f2 X ΝΑ2 > f3 X ΝΑ3 where f 1, f2 and f3 are the wavelengths λ 1 to λ of the objective lens, respectively The focal length of 3, and NAI, NA2, and NA3 are respectively used to record or reproduce the first, second, and third discs, where the third area provides a diffraction action for the second light flux. 6 · If the optical pickup device of item 5 of the patent application satisfies the following expression, • 0.75 ^ ΝΑ1 ^ 0.90 0.60 ^ ΝΑ2 ^ 0.70 0.43 $ ΝΑ3 S 0.55. 7 · If the optical pickup device in the fifth item of the patent application satisfies the following expression, 0.65 ^ ΝΑ1 ^ 0.70 0.60 ^ ΝΑ2 ^ 0.63 0.43 S ΝΑ3 S 0.55. 8. If the optical pickup device according to item 4 of the patent application satisfies the expression of -68- 200532679 (4), f2 x NA2 > fl χ ΝΑΙ > f3 χ ΝΑ3, where fl, f2, and f3 are objective lenses, respectively. The focal lengths of the wavelengths λ 1 to λ 3, and NAI, NA2, and NAA are respectively used for recording or reproducing the first, second, and third discs, wherein the third region provides a diffraction action for the first light flux. 9. If the optical pickup device of the patent application item 8 satisfies the following expression of B, 0.64 ^ ΝΑ1 ^ 0.65 0.64 ^ ΝΑ2 ^ 0.70 0.43 S ΝΑ3 $ 0.55 〇10. Such as the optical pickup device of the patent application item 1 Wherein, the first diffraction structure includes: a plurality of annular regions, the center of which is on the optical axis, and does not provide a substantial phase difference for the first light flux and the second light flux passing through the second region, the first diffraction structure Each of the plurality of annular regions includes a step structure, the step structure includes a predetermined number of discontinuous portions and the step portion. The second diffraction structure includes: a plurality of annular regions, the center of which is in the light On-axis' and do not provide a substantial phase difference for the first luminous flux and the second luminous flux passing through the third region -69- 200532679 (5) each of the plurality of annular regions of the second diffraction structure includes a one-step structure, The step structure includes a predetermined number of discontinuous portions and a predetermined number of step portions. 11. If the optical pickup device of the item 10 of the patent application scope satisfies the following expression, 4.8 X d ^ dl ^ 5.2 X d? 2 ^ M1 ^ 4 1.9 xd ^ d2 ^ 2.1 xd, 4 ^ M2 ^ 6 _ where n 1 represents the diffraction coefficient of a diffractive optical element with a wavelength λ 1, d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure, and M 1 is an integer and is at the first diffraction structure D2 is the step depth of the step portion in the second diffraction structure along the optical axis, M2 is an integer and is the number of discontinuities in the second diffraction structure, And d satisfies d = λ 1 / (nl-1). 1 2 · If the optical pickup device of the 10th patent application scope satisfies the following expressions: • 4.8 X d ^ dl ^ 5.2 xd? 2 ^ M1 ^ 4 0.9 xd ^ d2 ^ 1. 1 x d9 M2 = 2 where n 1 represents the diffraction coefficient of a diffractive optical element with a wavelength λ 1, d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure, and M 1 is an integer and is at the first diffraction structure D2 is the step depth of the step portion in the second diffraction structure along the optical axis, M2 is an integer and is the number of discontinuities in the second diffraction structure, And d satisfies d = Al / (nl-l). 1 3. If the optical pickup device of item 10 of the scope of patent application satisfies -70- 200532679 (6) The following expression, fl χ ΝΑΙ > f2 χ NA2 > f3 x NA3, where f 1, f2 and f3 are respectively Is the focal length of the objective lens from wavelengths A i to λ 3, and NA 1, Ν A2, and NA 3 are used to record or reproduce the first, second, and third discs respectively, where the third area provides the second luminous flux A diffraction action. 1 4 · If the optical pickup device of item 13 of the patent application scope satisfies the following expression, 0.75 ^ NA1 ^ 0.90 0.60 ^ NA2 ^ 0.70 0.43 $ NA3 € 0.55. 1 5 · If the optical pickup device in item 13 of the scope of patent application satisfies the following expression, 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 $ NA3 S 0.55. 16 · If the optical pickup device of the 10th patent application scope satisfies the following expression, f2 χ NA2 > fl χ ΝΑΙ > f3 χ NA3 where Π, f2 and f3 are the wavelengths χ 1 to of the objective lens, respectively; l 3 focus length, and NAI, NA2, and NA3 are used to record or reproduce the first, second, and third discs, respectively, -71-200532679 (7) where the third area provides a diffraction for the first luminous flux action. 17. If the optical pickup device of the 16th item of the patent application satisfies the following expression, 0.64 ^ NA1 ^ 0.65 0.64 ^ NA2 ^ 0.70 0.43 S NA3 $ 0.55. 18. For example, the optical pickup device of the first patent application scope satisfies the following expression p, 3 70nm ^ λ 1 440nm 620nm ^ 690nm 7 50nm S λ3 S 820nm. 19. The optical pickup device of claim 1, wherein the objective optical system includes the diffractive optical element. 20. —An optical pickup device for recording and / or reproducing information on an information recording surface of an optical disc having a protective substrate with a predetermined thickness and including and / or regenerating, comprising: a first light source emitting a first luminous flux having a wavelength λΐ 'To record and / or reproduce information on the optical recording surface of the first optical disc with a protective substrate having a thickness t1; a second light source emitting a second luminous flux having a second wavelength λ2 (λ2 > λΐ) for Record and / or reproduce information on the optical recording surface of a second optical disc with a protective substrate having a thickness of t2 (t2 2tl); a third light source having a third luminous flux having a wavelength λ3 (λ3 > λ2) for -72- 200532679 of the third optical disc with a protective substrate with a thickness of t3 (t3 > t2) (8) Learn the information on the surface first to record and / or reproduce; a diffractive optical element for transmitting the first To the third luminous flux; and an objective optical system having a light converging element to converge the luminous fluxes passing through the table 1 to the table 2 of the diffractive optical element onto the first to third optical discs, respectively, wherein The diffractive optical element includes a first region whose center is on the optical axis and includes the second diffractive structure; the second region is disposed outside the first region along a direction perpendicular to the optical axis in a ring shape. Forming, and including a second diffractive structure; a third region, formed in a ring shape along the direction perpendicular to the optical axis, outside the second region; the first region will pass through the first region and the light converge The first to third luminous fluxes of the element are respectively formed as convergent light spots on the information recording surfaces of the first to third discs, and the second region will pass through the second region and the first to third optical convergent elements. The first and second luminous fluxes are formed as convergent light spots on the information recording surfaces of the first and second discs, respectively, and the first to third luminous fluxes that do not pass through the first region and the light converging element are respectively formed. The third luminous flux is formed as a convergent light spot on the information recording surface of the third disc, and the third region will pass through the third region and the first to third luminous fluxes of the light converging element -73- 20053267 One of the first luminous flux and the second luminous flux in 9 (9) is formed as a convergent light spot on the information recording surface corresponding to the optical disc, and the first to third portions that will not pass through the third region and the light converging element The third luminous flux among the luminous fluxes and the first luminous flux and the second luminous flux of the other are formed as convergent light spots on the information recording surfaces of the corresponding optical discs between the first to third discs. 21. The optical pickup device of claim 20, wherein B the diffractive optical element includes an optical unit, and an optical surface of the optical element includes a second region and a third region. 22. The optical pickup device according to claim 20, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a second region, and the opposing optical surface includes a third region. 23. As for the optical pickup device of claim 20, the first diffractive structure provides a diffractive action for a second light flux passing through the first area, and φ the second diffractive structure provides a pass for passing through the second area. The second light flux and the third light flux provide a diffraction action. 24. The optical pickup device of claim 20, wherein the first diffractive structure includes: a plurality of annular regions, the center of which is on the optical axis, and does not affect the first luminous flux and the first luminous flux passing through the first region. Three luminous fluxes provide a substantial phase difference. Each of the plurality of annular regions of the first diffraction structure includes a step structure. The step structure includes a predetermined number of discontinuous portions and step portions. -74-200532679 (10 ) The second diffraction structure includes: a plurality of annular regions, the center of which is on the optical axis, and does not provide a substantial phase difference for the first luminous flux passing through the second region. Each of the plurality of annular regions includes a step The step structure includes a predetermined number of discontinuous portions and a predetermined number of step portions. 25. For example, the optical pickup device of the 24th scope of the patent application satisfies the following expression, 1.9 X d ^ dl ^ 2.1 X d5 4 ^ M1 ^ 6 4.8 xd ^ d2 ^ 5.2 xd? 4 ^ M2 ^ 6 where n 1 represents The diffraction coefficient of the diffractive optical element at the wavelength λ 1, d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure, and M 1 is an integer and is a non-zero value in the first diffraction structure. The number of continuous parts, d2 is the step depth of the step part in the second diffraction structure along the optical axis, M2 is an integer and is the number of discontinuous parts in the second diffraction structure, and d satisfies d = Al / (nl-1). 26. For example, the optical pickup device of the 24th scope of the patent application satisfies the following expression, 1.9 X dSdlS2.1 X d, 4SM1S6 0.9xd ^ d2 ^ 1.1xd92 ^ M2 ^ 5 where η 1 represents the diffraction optics of the wavelength λ 1 The diffraction coefficient of the element, d 1 represents the depth of the step portion in the optical axis direction in the first diffraction structure, M 1 is an integer and the number of discontinuous portions in the first diffraction structure, d2- 75- 200532679 (11) is the step depth of the step portion in the second diffraction structure along the optical axis, M 2 is an integer and is the number of discontinuous portions in the second diffraction structure, and d Meet d = Al / (nl-l). 2 7 · The optical pickup device according to item 20 of the patent application scope, wherein the second area is divided into at least two areas, and the areas include a region 2 A which is a center circle and whose center is on the optical axis. Region 2 B is a concentric circle and its center is on the optical axis. The region g of region 2A is constructed closer to the optical axis than region 2B. The second diffraction structure formed in region 2 A has The second diffraction structure on the region 2B has a different shape. 28. The optical pickup device according to item 20 of the patent application satisfies the following expression, 3 70nm ^ λ 1 440nm 620nm ^ 690nm 7 50nm S λ 3 S 820nm. φ 29. The optical pickup device of claim 20, wherein the objective optical system includes the diffractive optical element. 30. An optical pickup device for recording and / or reproducing information on an information recording surface of an optical disc with a protective substrate having a predetermined thickness, comprising: a first light source emitting a first luminous flux having a wavelength λΐ, and Record and / or reproduce information on the optical recording surface of the first optical disc with a protective substrate having a thickness t1; a second light source emitting a second wavelength Λ2 (λ2 > λΐ) of -76- 200532679 (12) Two luminous fluxes for recording and / or reproducing information on the optical recording surface of a second optical disc with a protective substrate having a thickness t2 (t2gtl); a third light source having a third luminous flux having a wavelength λ3 (λ3 > λ2) To record and / or reproduce information on the optical recording surface of a third optical disc with a protective substrate having a thickness t3 (t3> t2); a diffractive optical element for transmitting the first to third luminous fluxes; and An objective optical system has a light converging element to converge the first to third light fluxes passing through the diffractive optical element onto the first to third optical discs respectively, wherein the The radiating optical element includes a first region whose center is on the optical axis; a second region which is arranged outside the first region along a direction perpendicular to the optical axis and is formed in a ring shape; a third region which is perpendicular to the The direction of the optical axis is formed outside the second region and is formed in a ring shape. Φ The first region, the second region, and the third region have mutually different optical characteristics for the first to third light fluxes, and the third region does not Two light fluxes passing through the third area and the first to third light fluxes of the light converging element are formed on the information recording surface of the corresponding disc so that the first area will pass the first area and the first to third light converging elements. The third luminous flux is formed as convergent light spots on the information recording surfaces of the first to third discs, respectively. The second region -77- 200532679 (13) will pass through the second region and the first to the third of the optical convergence element. The first and second light fluxes of the three light fluxes are formed as convergent light spots on the information recording surfaces of the first and second discs, respectively, and do not converge with the light through the first region The third luminous flux among the first to third luminous fluxes of the element is formed as a convergent light spot on the information recording surface of the third disc. The third region | will pass through the third region and the first to One of the first light flux and the second light flux among the three light fluxes forms a convergent light spot on the information recording surface of the corresponding disc between the first and second discs, and does not pass through the third area and The third luminous flux among the first to third luminous fluxes of the light converging element, and the first luminous flux and the second luminous flux of the other are provided on the information recording surface of the corresponding disc between the first to third discs. Formed as a convergent light spot. φ 31. The optical pickup device according to item 30 of the scope of patent application, wherein the optical pickup device satisfies the following expression, 3 7Onm ^ λ 1 ^ 440nm 620nm ^ λ 690nm 7 5 0 nm ^ λ 820n m The second region contains A first diffractive structure having a plurality of annular regions, the centers of which are on the optical axis to provide a diffractive action to one of the first to third luminous fluxes, and a plurality of the first diffractive structures Each of the annular regions includes a step structure -78- 200532679 (14), the step structure includes a predetermined number of discontinuous portions and step portions, and the third region includes a second winding having a plurality of annular regions. Structure, the centers of the annular regions are on the optical axis and provide a diffractive action to one of the first to third luminous fluxes, and unlike the first diffractive structure, most of the rings of the second diffractive structure Each of the shape regions includes a step structure with a preset number of discontinuous portions and step portions, and the third region will not pass between the third region and the first to third luminous fluxes of the light converging element. Second luminous flux and third The light flux and the information recording surfaces of the second and third discs form convergent light spots. 32. The optical pickup device according to item 30 of the patent application scope, wherein the optical pickup device satisfies the following expression, 370ηηι ^ λ 1 ^ 440nm 620nm ^ λ 690nm 75 0nm ^ λ 820nm The first region includes a ring having a plurality of rings The first diffractive structure of the morphous region, the center of the annular regions is on the optical axis and provides a diffractive action to one of the first to third luminous fluxes, each of the plurality of annular regions of the first diffractive structure Each includes a step structure, the step structure includes a predetermined number of discontinuous portions and step portions, the second region includes a second diffraction structure having a plurality of annular regions, and the centers of the annular regions are The optical axis provides a diffractive action to one of the first to third luminous fluxes, and is different from the first diffractive structure. Each of the plurality of annular regions of the second diffractive structure includes a one-step structure. A predetermined number of discontinuous sections and step sections of the step structure, -79- 200532679 (15) the third region will not pass through the third region and the second luminous flux and the first luminous flux between the first to third luminous fluxes of the light converging element Sanguangtong The converged light spot is formed on the surface of the second and third information recording disc. 33. The optical pickup device of claim 30, wherein the diffractive optical element includes an optical unit, and an optical surface of the optical element includes a second region and a third region. 34. The optical pickup device of claim 30, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a second region, and the opposite optical surface includes a third region. 3 5. If the optical pickup device in the 30th scope of the patent application satisfies the following expression, 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 S NA3 $ 0.55, where ΝΙΙ, NA2 and NA3 are used for recording or reproduction, respectively. Number of apertures of the first, second and third discs. 36. If the optical pickup device in the 30th scope of the application for the patent satisfies the following expression, 0.64 ^ NA1 ^ 0.65 0.64 ^ NA2 ^ 0.70 0.43 S NA3 $ 0.55, where ΝΑΙ, NA2 and NA3 are respectively used as the first recording or reproduction Number of apertures of the second, third and third discs. 37. A diffractive optical element used in an optical pickup device, using -80-V: 200532679 (16) to record and / or reproduce information on an information recording surface of an optical disc having a protective substrate with a predetermined thickness, Including: a first light source emitting a first light flux having a wavelength λ 1 to record and / or reproduce information on an optical recording surface of a first optical disc having a protective substrate having a thickness t1; a second light source emitting an A second luminous flux of a second wavelength λ2 (λ2 > λΐ) for recording and / or reproducing information on the optical recording surface of a second B disc with a protective substrate having a thickness t2 (t22 tl); a third light source A third luminous flux with a wavelength λ3 (λ3 > λ2) for recording and / or reproducing information on the optical recording surface of a third optical disc with a protective substrate having a thickness t3 (t3 >t2); a diffractive optical An element for transmitting the first to third light fluxes; and an objective optical system having a light converging element for converging the first to third light fluxes passing through the diffractive optical element to Above the first to third optical discs, wherein the diffractive optical element includes a first region whose center is on the optical axis; a second region is disposed outside the first region along a direction perpendicular to the optical axis; It is formed in a ring shape and includes a first diffraction structure; a third region is formed in a ring shape along the direction perpendicular to the optical axis outside the second region and includes a second diffraction structure; the The first region will be formed as a convergent light spot on the information recording surfaces of the first to third discs through the first region and the first to third luminous fluxes of the light converging element '-81-200532679 (17) The two regions will be formed as convergent light spots on the information recording surfaces of the first and second discs through the second region and the first and second luminous fluxes of the first to third luminous fluxes of the optical convergent element, respectively. Forming the third luminous flux among the first to third luminous fluxes passing through the first region and the light converging element as a convergent light spot on the information recording surface of the third disc, The third region will pass the information of the corresponding optical disc between the first and second discs, among the first and second luminous fluxes of the third region and the first to third luminous fluxes of the light converging element. A convergent light spot is formed on the recording surface, and the third luminous flux and the first luminous flux and the second luminous flux of the other among the first to third luminous fluxes passing through the third region and the light converging element are not interposed therebetween. The information recording surfaces of the corresponding discs between the first to third discs are formed as convergent light spots. 38. The diffractive optical element according to item 37 of the scope of patent application, wherein the diffractive optical element includes an optical unit, and an optical surface of the optical element includes a second region and a third region. 39. The diffractive optical element according to item 37 of the patent application scope, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a second region, and the opposite optical surface includes a third region . 40. If the diffractive optical element in item 37 of the scope of patent application, the first diffractive structure provides a diffractive action for the third luminous flux passing through the second area -82- 200532679 (18), and the second The diffraction structure provides another diffraction action for the second light flux and the first light flux passing through the third region. 4 1. The diffractive optical element according to item 37 of the scope of patent application, wherein the first diffractive structure includes: a plurality of annular regions, the center of which is on the optical axis, and is not for the first passing through the second region The luminous flux and the second luminous flux provide a substantial phase difference. Each of the plurality of annular regions of the first diffraction structure includes a step structure. The step structure includes a predetermined number of discontinuous portions and a step portion. The diffractive structure includes: a plurality of annular regions, the center of which is on the optical axis, and does not provide a substantial phase difference for the first luminous flux and the second luminous flux passing through the third region, and the plurality of annular regions of the second diffractive structure Each of the regions includes a first-order structure including a predetermined number of discontinuous portions and a predetermined number of step portions. 42. If the diffractive optical element according to item 41 of the scope of patent application meets the following expression, 4,8 X dS dl € 5.2 X d, Ml g 4 1 .9 x d2 ^ 2.1 xd, M2 ^ 6 where n 1 represents the wavelength; the diffraction coefficient of the diffractive optical element of l 1; d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure; M 1 -83- 200532679 (19) is an integer And for the number of discontinuous parts in the first diffraction structure, d2 is the step depth along the optical axis in the step part in the second diffraction structure, M2 is an integer and is the second diffraction structure The number of discontinuous parts in d and d satisfies d = λ 1 / (η 1-1). 43. If the diffractive optical element in item 4 of the scope of the patent application satisfies the following expression, 4.8 X d ^ dl ^ 5.2 xd? 2 ^ M1 ^ 4 • 0.9xdgd2 $ l.lxd, M2 = 2 where n 1 represents Diffraction coefficient of a diffractive optical element with a wavelength of λ 1, d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure, 'M 1 is an integer and is a negative value in the first diffraction structure The number of consecutive parts' d2 is the step depth of the step part in the second diffraction structure along the optical axis' M2 is an integer and is the number of discontinuous parts in the second diffraction structure 'and d satisfies d = Al / (nl-l). 44. If the diffractive optical element in item 37 of the scope of patent application 'satisfies the following expression, 3 7 0ηm ^ λ 1 ^ 440nm 620nλ 2 ^ 690nm 7 5 0 nm ^ λ 3S 820nm o 45. 3 Diffractive optical element of 7 terms' satisfies the following expression, 0.75 ^ NA1 ^ 0.90 0.60 ^ NA2 ^ 0.70 0.43 S NA3 $ 0.55, -84- 200532679 (20) where NA1, NA2, and the first, second, and third The third area of the disc is for the second 46. As shown in the following expression of the patent application scope, 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 0.43 g NA3 $ 0.55, where Α1, Ν2 and the first, second, and The third area of the third disc is for the second 47. As shown in the following expression of the patent application scope, 0.64 ^ ΝΑ1 ^ 0.65 0.64 ^ ΝΑ2 ^ 0.70 0.43 S ΝΑ3 S 0.55, where ΝΑ1, Ν2 and the first, second, and The third area of the third disc is for the second 4 8. — A kind of optical pickup used to record and / or reproduce the protective base information with a predetermined thickness, a first light source, and a light having a thickness t1 Protective substrate NA 3 Zhi were used for the recording or reproducing aperture number, providing diffraction light flux action. The diffractive optical elements of item 3 and 7 meet the requirements of the N A 3 series. They are used to record or reproduce data apertures and provide a diffraction action for the luminous flux. The diffractive optical element of item 7 meets the requirements of NA3 series. It is used to record or reproduce the data aperture and provide the diffraction action of the luminous flux. Take the diffractive optical element in the device and use the information on the bottom surface of the optical disc to record: ▲ contains: the first luminous flux with a wavelength of λ 1 to give -85- 200532679 (21) information on the optical recording surface of the first disc Recording and / or reproducing; a second light source emitting a second luminous flux having a second wavelength λ2 (λ2 > λΐ) for applying an optical recording surface on a second optical disc having a protective substrate having a thickness t2 (t2 ^ tl) Information is recorded and / or reproduced; a third light source having a third luminous flux having a wavelength λ3 (λ3 > λ2) for applying an optical recording surface on a third optical disc having a protective substrate having a thickness t3 (t3 > t2) Information is recorded and / or reproduced; g — a diffractive optical element for transmitting the first to third luminous fluxes; and an objective optical system having a light converging element to pass the first through the diffractive optical element The third luminous flux converges onto the first to third optical discs respectively, wherein the diffractive optical element includes a first region whose center is on the optical axis and includes the second diffractive structure; the second region, along the A direction perpendicular to the optical axis is formed outside the first region φ and formed in a ring shape, and includes a second diffraction structure; a third region is disposed in the second region along a direction perpendicular to the optical axis. The outer side is formed in a ring shape; the first region passes through the first region and the first to third luminous fluxes of the light converging element are respectively formed as convergent light spots on the information recording surfaces of the first to third discs. The second area passes the first area and the second area of the first to third luminous fluxes of the optically converging element on the first and second discs, respectively, at -86- 200532679 (22) information recording surface Formed as a convergent light spot, and a third light flux among the first to third light fluxes passing through the first region and the light converging element is not formed as a convergent light spot on the information recording surface of the third disc, the third The region forms one of the first luminous flux and the second luminous flux passing through the third region and the first to third luminous fluxes of the light converging element on a g information recording surface corresponding to the optical disc as a convergence Point, and do not pass the third luminous flux among the first to third luminous fluxes passing through the third region and the light converging element, and the first luminous flux and the second luminous flux of the other between the first to third discs. The information recording surface of the corresponding disc is formed as a convergent light spot. 49. The diffractive optical element according to claim 48, wherein the diffractive optical element includes an optical unit, and an optical surface of the optical element includes a second region and a third region. φ 5 0 · The diffractive optical element according to item 48 of the patent application scope, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a second region, and the opposite optical surface includes a third region region. 5 1. If the diffractive optical element according to item 48 of the scope of patent application, the first diffractive structure provides a diffractive action for the second luminous flux passing through the first area, and the second diffractive structure is suitable for passing the first The second luminous flux and the third luminous flux of the two regions provide a diffraction action. 5 2 · If the diffractive optical element according to item 48 of the scope of patent application, -87- 200532679 (23) wherein the first diffractive structure includes: a plurality of annular regions, the center of which is on the optical axis' and is not correct A substantial phase difference is provided by the first luminous flux and the third luminous flux in the first region. Each of the plurality of annular regions of the first diffraction structure includes a step structure, the step structure includes a predetermined number of discontinuous portions. And the step portion, the second diffraction structure includes: a plurality of annular regions, the center of which is on the optical axis, and does not provide a substantial phase difference to the first luminous flux passing through the second region. Each system includes a one-step structure including a predetermined number of discontinuous portions and a predetermined number of step portions. 53. If the diffractive optical element in the 52nd scope of the patent application satisfies the following expression, • 1.9 X dl ^ 2.1 X d? Ml ^ 6 4.8 xd ^ d2 ^ 5.2 x d5 4 ^ M2 ^ 6 where n 1 represents the wavelength Diffraction coefficient of the diffractive optical element of λ 1, d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure, M 1 is an integer and is a discontinuity in the first diffraction structure The number of parts, d2 is the step depth of the step part in the second diffraction structure along the optical axis 'M2 is an integer and is the number of discontinuous parts in the second diffraction structure', and d satisfies d = Al / (nl-1). 5 4. If the diffractive optical element in item 52 of the scope of patent application, meets -88- 200532679 (24) The following expression, 1.9 X dg dl $ 2.1 X d, 4 $ Ml € 6 0.9xd ^ d2 ^ 1.1 xd92 ^ M2 ^ 5 where n 1 represents the diffraction coefficient of a diffractive optical element with a wavelength of λ 1 and d 1 represents the depth of the step portion in the direction of the optical axis in the first diffraction structure. M 1 is an integer and is The number of discontinuous parts in the first diffraction structure, d2 is the step depth along the optical axis in the step portion in the second diffraction structure, g M2 is an integer and is in the second diffraction structure Number of discontinuous parts, and d satisfies d = Al / (nl-1). 5 5 · The diffractive optical element according to item 48 of the scope of patent application, wherein the second region is divided into at least two regions, and the regions include a region 2A which is concentric circles and whose center is on the optical axis. Region 2 B is a concentric circle and its center is on the optical axis. The region 2A is constructed closer to the optical axis than the region 2B. The second diffraction structure formed in the region 2 A has the same shape as that formed in the region. The second diffraction structure on φ 2B has a different shape. 5 6. If the diffractive optical element in item 48 of the patent application satisfies the following expression, 370nm ^ λ 440ηm 6 2 0 nm ^ λ 690n m 750nmg λ 3 $ 820nm ο 5 The diffractive optical element satisfies the following expressions: 0.75 ^ NA1 ^ 0.90 -89- 200532679 (25) 0.60 ^ NA2 ^ 0.70 0.43 S NA3 S 0.55, where NA 1, NA 2 and NA 3 are used as recording or reproduction Number of apertures of the first, second and third discs. 5 8 · If the diffractive optical element in item 48 of the patent application scope satisfies the following expression, 0.65 ^ NA1 ^ 0.70 _ 0.60 $ NA2 S 0.63 0.43 g NA3 S 0.55, where ΝΙΙ, NA2 and NA3 are used as records Or reproduce the apertures of the first, second and third discs. 59. If the diffractive optical element in the 48th scope of the patent application satisfies the following expression, 0.64 ^ NA1 ^ 0.65 0.64 ^ NA2 ^ 0.70 φ 0.43 g NA3 S 0.55, where ΝΙΙ, NA2 and NA3 are used for recording or reproduction, respectively. Number of apertures of the first, second and third discs, wherein the third region provides a diffraction action for the second light flux. 60. A diffractive optical element used in an optical pickup device for recording and / or reproducing information on an information recording surface of an optical disc with a protective substrate having a predetermined thickness, comprising: a first light source, The first luminous flux of wavelength λ 'is used to record and / or reproduce -90- 200532679 (26) information on the optical recording surface of the first optical disc with a protective substrate having a thickness t1; a second light source emitting a light having a second wavelength λ2 (λ2 > λΐ) is a second light flux for recording and / or reproducing information on the optical recording surface of a second optical disc with a protective substrate having a thickness t2 (t2gtl); a third light source having a wavelength λ3 ( λ3 > Λ2) The third luminous flux is used to record and / or reproduce the information on the optical recording surface of the third optical disc with a protective substrate of thickness t3 (t3 >t2); _ a diffractive optical element for Transmitting the first to third luminous fluxes; and an objective optical system having a light converging element to converge the first to third luminous fluxes passing through the diffractive optical element to the first to the third, respectively Above the three optical discs, wherein the diffractive optical element includes a first region whose center is on the optical axis; a second region which is arranged outside the first region along a direction perpendicular to the optical axis and is formed in a ring shape; φ The third region is formed in an annular shape along the direction perpendicular to the optical axis and is arranged outside the second region; the first region, the second region, and the third region have mutually different first to third luminous fluxes. Light characteristics, the third region does not form two light fluxes passing through the third region and the first to third light fluxes of the light converging element on the information recording surface of the corresponding disc as the first region will pass through the first region And the first to third luminous fluxes of the light converging element are formed as convergent light spots on the information recording surfaces -91-200532679 (27) of the first to third discs, respectively, and the second region will pass through the second region and the The first and second luminous fluxes of the first to third luminous fluxes of the optical convergence element are formed as convergent light spots on the information recording surfaces of the first and second discs, respectively, and The third luminous flux passing through the first region and the first to third luminous fluxes of the light converging element is formed as a convergent light spot on the information recording surface of the third disc, and the third region will pass through the third region and the light One of the first luminous flux and the second luminous flux among the first to third luminous fluxes of the converging element is formed as a convergent light spot on the information recording surface of the corresponding disc between the first and second discs, and The third luminous flux passing through the third region and the first to third luminous fluxes of the light converging element, and the first luminous flux and the second luminous flux% of the other are not placed between the first to third discs. The information recording surface of the corresponding disc is formed as a convergent light spot. 6 1. The diffractive optical element according to item 60 of the scope of patent application, wherein the optical pickup device satisfies the following expression: 3 70nm ^ λ 1 ^ 440nm 620nm ^ λ 690nm 7 5 0nm ^ λ 820nm First diffraction structure of a plurality of annular regions. The centers of the annular regions are provided on the optical axis to provide diffraction action to the first to -92- 200532679 (28) one of the second light fluxes. Each of the plurality of annular regions of the structure includes a step structure, the step structure includes a predetermined number of discontinuous portions and step portions, and the third region includes a second diffraction structure having a plurality of annular regions, The centers of the annular regions are on the optical axis and provide a diffractive action to one of the first to third luminous fluxes, and are different from the first diffractive structure. Each includes a step structure, a predetermined number of discontinuous parts and step parts, and the third region will not pass through the third region and the first to third luminous fluxes of the light convergence element. Second luminous flux and third luminous flux The converged light spot is formed on the surface of the second and third information recording disc. 62. The diffractive optical element according to item 60 of the application, wherein the optical pickup device satisfies the following expression: 3 70nm ^ λ 1 ^ 440nm 620nm ^ λ 690nm • 75 0nm ^ λ 3 ^ 820nm The first region contains a A first diffractive structure with a plurality of annular regions, the centers of which are on the optical axis and provide a diffractive action to one of the first to second light fluxes. Each of the shape regions includes a step structure, the step structure includes a predetermined number of discontinuous portions and step portions, the second region includes a second diffraction structure having a plurality of annular regions, and the annular regions The center is on the optical axis and provides a diffractive action to one of the first to third luminous fluxes, and is different from the first diffractive structure. -93- 200532679 (29) Most of the second diffractive ring structure Each of the regions includes a step structure, a predetermined number of discontinuous portions and step portions of the step structure. The third region will not pass through the third region and the first to third luminous fluxes of the light converging element. Second luminous flux and third Second and third flux and the information recording disc is formed of a light spot converged on the surface. 63. The diffractive optical element according to item 60 of the patent application, wherein the diffractive optical element includes an optical unit, and an optical g surface of the optical element includes a second region and a third region. 64. The diffractive optical element according to item 60 of the patent application, wherein the diffractive optical element includes an optical unit, an optical surface of the optical element includes a second region, and the opposing optical surface includes a third region. 65 · If the diffractive optical element in item 60 of the patent application satisfies the following formula, 0.65 ^ NA1 ^ 0.70 0.60 ^ NA2 ^ 0.63 • 0.43 S NA3 $ 0.55, where ΝΑΙ, NA2 and NA3 are used as records or Number of apertures of the first, second and third discs are reproduced. 66. If the diffractive optical element of item 60 of the patent application satisfies the following formula, 0.64 g NA1 '0.65 0.64 ^ NA2 ^ 0.70 0.43 $ NA3 S 0.55, where ΝΑΙ, NA2 and NA3 are used for recording or reproduction respectively -94-, 200532679 ^ (30) Number of apertures of the first, second and third discs. -95-